ci: remove the auto-tag-on-merge release workflow (#13)

release.yaml bumped and pushed a version tag on every push to main via
anothrNick/github-tag-action, so routine merges (CI, docs) would mint
releases. Tagging should be deliberate. Remove it; cut tags manually
when actually releasing.

(It had also been failing on recent merges, so no tags were created.)

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Author: reuvenharrison