chore: require rubocop-minitest 0.39

[atesgoral]

TL;DR

Require rubocop-minitest 0.39.0 or newer so Minitest/AssertEmptyLiteral uses its newer default disabled state.

Context

Clean main reported 35 Minitest/AssertEmptyLiteral offenses with rubocop-minitest 0.38.2. That cop was disabled by default in rubocop-minitest 0.39.0 because assert_empty can hide whether the intended expected literal was [] or {}.

Changes

• Add a minimum rubocop-minitest version of 0.39.0 in the Gemfile.
• Leave the existing assertions unchanged.

Tophatting

• GEM_HOME="$PWD/.gem-test" GEM_PATH="$PWD/.gem-test:/nix/store/jh918yiwd5cs4pjg005ac32m2q7ckw3l-ruby-4.0.5/lib/ruby/gems/4.0.0" bundle exec rake rubocop
• GEM_HOME="$PWD/.gem-test" GEM_PATH="$PWD/.gem-test:/nix/store/jh918yiwd5cs4pjg005ac32m2q7ckw3l-ruby-4.0.5/lib/ruby/gems/4.0.0" bundle exec rake test
• git diff --check

[koic]

Minitest/AssertEmptyLiteral is disabled by default because replacing [] and {} can make it harder to see which literal is being asserted, which may reduce readability.
rubocop/rubocop-minitest#346

I believe this case is no longer flagged. Is that still the case?

[atesgoral]

@koic After upgrading rubocop-minitest, these assertions are no longer flagged.