Drop --allow-branch and harden the publish plan count
Review flagged `--allow-branch "*"` as letting a release publish from any branch. It does neither thing. cargo-workspaces only consults it from GitOpt::validate, whose sole caller is the versioning path, and --publish-as-is skips that path entirely. The same check rejects a detached HEAD before it ever tests the pattern, so on a tag checkout the flag could never have helped either. Verified against 0.4.2's source and by dry running from a detached worktree at v1.0.0 without it. The plan count was worth hardening. Inside `echo "count=$(...)"` a failing python3 still leaves exit status 0 and writes an empty count, and GitHub coerces an empty string to 0 in `!= '0'`, so a broken plan step would quietly skip the publish and report that everything was already on crates.io. Assigning first lets `bash -e` abort instead. Also records why the publish interval is there. Co-Authored-By: siGit Code <noreply@sigit.si>