Bump pydantic-settings from 2.15.0 to 2.16.0

[dependabot]

Bumps pydantic-settings from 2.15.0 to 2.16.0.

Release notes

Sourced from pydantic-settings's releases.

v2.16.0

Highlights

Breaking changes and behavior changes

• Python 3.10 is no longer supported (#1003). pydantic-settings now requires Python 3.11+, since 3.10 reaches end of life this month. The tomli fallback is gone in favor of stdlib tomllib; the toml extra is kept as an empty extra so pip install pydantic-settings[toml] keeps working.
• python-dotenv>=1.2.2 is now required (#971) to pick up the fix for CVE-2026-28684.
• Aliases are ignored in every source when validate_by_alias=False (#1033). Env vars, secrets, CLI flags and defaults now use only field names, matching pydantic. An env var named after the alias is now ignored instead of raising extra_forbidden, and the CLI exposes --apple rather than --pomo.
• validation_alias takes precedence over alias (#1038). When the two differ, values from JSON/YAML/TOML files and the CLI were silently ignored; they now load. CLI help lists the validation_alias flag first, and CliApp.serialize emits it.
• CLI case-insensitivity only lowercases registered options (#1036). With case_sensitive=False, args after -- and those captured by CliUnknownArgs keep their case (-Xmx4G no longer becomes -xmx4g). Unrecognized options are now reported as typed (--NOPE instead of --nope).
• JSON and YAML config files are read as UTF-8 by default (#955) instead of the locale encoding, completing the secrets-file fix from 2.15.0. json_file_encoding/yaml_file_encoding still override it.
• Discriminated union defaults are partially updated again (#997). This reverts the 2.15.0 regression with nested_model_default_partial_update=True: the default is only dropped when the incoming value selects a different union member.

New features

• Python 3.15 and pydantic 2.14 support (#1026, #1029, #1022). pydantic 2.14 broke CliApp.run and validate_by_alias=False handling; both are fixed.
• Cached settings instances via Settings.settings_cached() and Settings.settings_clear_cache() (#952). These give you a process-local singleton per settings class without hand-rolling lru_cache wrappers. Calling the class directly still builds a fresh instance.
• AWS Systems Manager Parameter Store source — AWSSystemsManagerSettingsSource (#941). It recursively reads every parameter under an ssm_path, with / mapping onto nested models. Install it with the new aws-systems-manager extra.
• env_file_depth (#940) lets a relative env_file be found in parent directories, mirroring pyproject_toml_depth. This is useful when scripts run from a subdirectory of a monorepo. It defaults to 0, which keeps the current behavior.
• CliVariadicArg for named variadic options (#949, #958). It accepts --param a b c in addition to repeated --param a --param b. Required fields need at least one value.

Bug fixes

CLI

• CliApp.serialize output now round-trips through CliApp.run for enums, tuples, dates and Decimals (#988), explicit None values (#981), empty containers (#1008), CliVariadicArg values (#976) and populated CliUnknownArgs fields, which previously raised IndexError (#992).
• Empty JSON arrays (--items []) now give an empty list instead of [''] (#994).
• Tuples, frozenset, MutableSequence and other collection subtypes are now treated as repeatable/variadic options (#972), and so are named collection type aliases such as TypeAliasType('Addrs', list[IPvAnyAddress]) (#1032).
• cli_exit_on_error=False is now honored in CliSubCommand parsers, which raise SettingsError instead of exiting (#977).
• CliSubCommand aliases keep their case with case_sensitive=False (#989).
• Each CliUnknownArgs field now receives only its own subcommand's leftover args (#1004).
• CliApp.format_help no longer crashes when cli_prefix is set in model_config (#945).

Type aliases and parsing

• Named union type aliases (TypeAliasType('V', list[int] | str)) now decode like their inline equivalents in env and dotenv sources, including under Optional, Annotated and custom validation aliases (#1006, #1030, #1041).
• Resolving a named Annotated type alias no longer mutates shared FieldInfo metadata, which made validators run twice on subclasses or after model_rebuild() (#979).
• A bare single-segment AliasPath('SOME_KEY') no longer tries to JSON-decode plain string values (#980).
• collections.abc.Set/MutableSet/typing.AbstractSet fields now JSON-decode env values (#973).
• A bare typing.Dict field with env_nested_delimiter no longer raises IndexError, which was a regression in 2.13.0 (#1009).
• Case-insensitive matching now works for nested pydantic dataclasses (#1010).

Dotenv, secrets and config files

• With extra='allow', a non-lowercase env_prefix is now stripped from dotenv extras (#959, #968).
• secrets_case_sensitive=True is now honored on Windows (#1001).
• An empty JSON config file is treated as an empty mapping instead of crashing (#947), matching YAML and TOML.
• TOML table headers: ~ paths are now expanded when checking that the file exists (#1034), and an explicit toml_table_header=() now overrides the model config to read the file root (#1027).

Cloud sources

• Azure Key Vault and GCP Secret Manager now honor env_parse_none_str (#1019, #1040).
• Azure Key Vault: dash_to_underscore=True now works for nested model fields (#1025).
• NestedSecretsSettingsSource now validates its specific constructor arguments (#975).

... (truncated)

Commits

• 8c259f4 Prepare release 2.16.0 (#1043)
• 4bc667a Keep case of non-option CLI args when case_sensitive=False (#1036)
• f75a805 Simplify alias resolution branch and test alias with AliasChoices/AliasPath (...
• cfdc558 Honor env_parse_none_str for GCP Secret Manager (#1040)
• 081d39f Fix config file and CLI values being ignored when alias differs from validati...
• c46ebc4 Expand home paths when checking TOML table headers (#1034)
• 6ea85e6 Decode optional Annotated named union aliases (#1041)
• ca9d7c4 Fix JSON decoding for optional named union aliases (#1030)
• b6ddda2 Fix CLI parsing for named collection type aliases (#1032)
• bedb60e Honor explicit empty TOML table header overrides (#1027)
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