chore: use `!` for breaking changes

[knqyf263]

Description

For clarity, we added the type BREAKING to the existing type of Conventional Commits, but Release Please recognizes only breaking changes indicated by the !.

feat!:, or fix!:, refactor!:, etc., which represent a breaking change (indicated by the !) and will result in a SemVer major.

https://github.com/googleapis/release-please/blob/ace2bd5dc778f83c33ad5dee6807db5d0afdba36/README.md?plain=1#L52-L53

Now, it's better to follow Conventional Commits.

Checklist

• [x] I've read the guidelines for contributing to this repository.
• [x] I've followed the conventions in the PR title.
• [ ] I've added tests that prove my fix is effective or that my feature works.
• [x] I've updated the documentation with the relevant information (if needed).
• [ ] I've added usage information (if the PR introduces new options)
• [ ] I've included a "before" and "after" example to the description (if the PR is a user interface change).

[simar7]

and will result in a SemVer major.

Just to clarify, will every breaking change will be a major version bump?

[knqyf263]

Just to clarify, will every breaking change will be a major version bump?

I believe not. We set "bump-minor-pre-major": true. https://github.com/aquasecurity/trivy/blob/648ead9553eb2cbeac90e3ef7330a70c352255ac/release-please-config.json#L5

// BREAKING CHANGE only bumps semver minor if version < 1.0.0 // absence defaults to false

https://github.com/googleapis/release-please/blob/ace2bd5dc778f83c33ad5dee6807db5d0afdba36/docs/manifest-releaser.md