Added Mode::EXECUTABLE flag to gradlew files

[gmazzo]

What are you trying to accomplish?

After #13579, we realised that the executable mode of gradlew was lost when dependabot updates the Gradle Wrapper binaries:

/Users/runner/work/_temp/9c8c4b16-87e9-4ad9-aa50-8fd0b4f2ccd7.sh: line 1: ./gradlew: Permission denied

https://github.com/gmazzo/gradle-codeowners-plugin/actions/runs/19988292200/job/57325370740?pr=251#step:4:21

Smoke tests PR: https://github.com/gmazzo/gradle-codeowners-plugin/pull/251/files

Anything you want to highlight for special attention from reviewers?

I'm assuming that setting file.mode = Mode.EXECUTABLE will be propagated to the PR creation, but needs validation from mantainers.

How will you know you've accomplished your goal?

Since I can't run (or don't know how) to run dependabot locally to open real PRs, I rely on smoke tests to validate the change.

The run with dependabot test reveals that now a new mode: 100755 is added into the output YAML:

Checklist

• I have run the complete test suite to ensure all tests and linters pass.
• I have thoroughly tested my code changes to ensure they work as expected, including adding additional tests for new functionality.
• I have written clear and descriptive commit messages.
• I have provided a detailed description of the changes in the pull request, including the problem it addresses, how it fixes the problem, and any relevant details about the implementation.
• I have ensured that the code is well-documented and easy to understand.