chore: update librarian version to v0.42.0

[suztomo]

Update librarian version to v0.42.0.

Included Librarian Updates

• chore(main): release 0.42.0 librarian#7524: chore(main): release 0.42.0
• chore(main): release 0.41.0 librarian#7473: chore(main): release 0.41.0
• fix(internal/librarian): update bulk release-please config for existing python libraries librarian#7508: fix(internal/librarian): update bulk release-please config for existing python libraries
• build(.github/workflows): separate java integration test into standalone job librarian#7489: build(.github/workflows): separate java integration test into standalone job
• ci(.github): increase timeout of php integration test librarian#7491: ci(.github): increase timeout of php integration test
• refactor(internal/config): remove nodejs_apis from NodejsPackage librarian#7487: refactor(internal/config): remove nodejs_apis from NodejsPackage
• build(.github): add test matrix for PHP librarian#7469: build(.github): add test matrix for PHP
• build(deps): bump google.golang.org/grpc from 1.82.1 to 1.83.1 librarian#7482: build(deps): bump google.golang.org/grpc from 1.82.1 to 1.83.1

[gemini-code-assist]

Code Review

This pull request updates the version field in the librarian.yaml configuration file from v0.40.0 to v0.42.0. There are no review comments to address, and I have no additional feedback to provide.