Update comments Dependabot reference link

[guspan-tanadi]

Replace this description with a description of what your PR is changing, adding, enabling, or disabling.

[!IMPORTANT] This repository is a testing suite that contains references to tests (in the registry directory) that are run with every commit to Flutter to verify that no breaking changes have been introduced (in the "customer_testing" shards). Your merged PR is not automatically run in the Flutter CI tree.

After merging this PR, you must send another PR to flutter/flutter updating dev/customer_testing/tests.version in that repo with the latest git commit SHA of the flutter/test repo.

See https://github.com/flutter/flutter/pull/162048 for details.

Pre-launch Checklist

• [x] I read the Contributor Guide and followed the process outlined there for submitting PRs.
• [x] I read the Tree Hygiene wiki page, which explains my responsibilities.
• [ ] I read the Flutter Style Guide recently, and have followed its advice.
• [x] I signed the CLA.
• [ ] I listed at least one issue that this PR fixes in the description above.
• [ ] I updated/added relevant documentation (doc comments with ///).
• [ ] I added new tests to check the change I am making, or this PR is test-exempt.
• [ ] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel on Discord.