Add support for 'bun.lock' in LOCK_FILE_TO_MANAGER

[brunocentanaro]

Add bun.lock Support

This PR adds support for the bun.lock file, which was previously not recognized (only bun.lockb was handled).

Before this change, projects using bun.lock triggered the following error:

setup-ci failed with unexpected error:
  No lock file found in repository root directory. Are you sure you are in a project directory?
  Make sure you generated lock file by installing project dependencies.
  You can check https://github.com/software-mansion/setup-ci/blob/master/docs/troubleshooting.md for potential solution.

After adding bun.lock to the lockfile detection list, the setup worked correctly in my tests without requiring any additional changes.