chore: bump pre-commit-hooks to v6.0.0

`pre-commit autoupdate` on the two non-ruff hook repos; the ruff repo
is excluded because its rev is pinned to uv.lock by
check-ruff-lockstep, and taskcluster_yml_validator is already current.

v6.0.0 removes only check-byte-order-marker and fix-encoding-pragma,
neither of which this config uses. The five hooks it does use
(check-executables-have-shebangs, check-merge-conflict, check-symlinks,
check-yaml, check-json) changed by import style alone between the two
tags -- typing.Sequence -> collections.abc.Sequence -- with no
behaviour change.

Author: dekobon

.pre-commit-config.yaml

@@ -1,6 +1,6 @@
 repos:
 -   repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: v5.0.0
+    rev: v6.0.0
     hooks:
     -   id: check-executables-have-shebangs
     -   id: check-merge-conflict