ci(release): add Homebrew

[WaterLemons2k]

What does this PR do?

Automatically bump Homebrew's ddns-go after release.

Fixes #740.

Motivation

#740

Additional Notes

Ref: https://github.com/Homebrew/actions/tree/master/bump-formulae#usage

One should use the Personal Access Token for token input to this Action, not the default GITHUB_TOKEN, because brew bump-formula-pr creates a fork of the formula's tap repository (if needed) and then creates a pull request.

Following https://docs.github.com/zh/actions/security-guides/encrypted-secrets#creating-encrypted-secrets-for-a-repository, please enter the Personal Access Token (workflow scope enabled) into the secret HOMEBREW_COMMITTER_TOKEN.