ci(bump): gracefully handle no bump-eligible commits

When commits like docs:, ci:, or build(deps): are pushed to master,
cz bump exits with code 21 (NO_COMMITS_TO_BUMP), failing the workflow.

Handle exit code 21 explicitly by setting bumped=false and exiting 0.
Subsequent changelog and release steps are now conditional on
bumped == 'true', so they are skipped when there is nothing to release.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: bearomorphism

.github/workflows/bumpversion.yml

@@ -38,18 +38,33 @@ jobs:
           git-user-email: "${{ steps.get-user-id.outputs.user-id }}+${{ steps.app-token.outputs.app-slug }}[bot]@users.noreply.github.com"
       - id: bump-version
         run: |
+          set +e
           cz bump --yes
+          exit_code=$?
+          set -e
+
+          if [ $exit_code -eq 21 ]; then
+            echo "No bump-eligible commits found, skipping release."
+            echo "bumped=false" >> $GITHUB_OUTPUT
+            exit 0
+          elif [ $exit_code -ne 0 ]; then
+            exit $exit_code
+          fi
+
+          echo "bumped=true" >> $GITHUB_OUTPUT
           git push --follow-tags
           new_version="$(cz version -p)"
           echo "new_version=$new_version" >> $GITHUB_OUTPUT
           new_version_tag="$(cz version -p --tag)"
           echo "new_version_tag=$new_version_tag" >> $GITHUB_OUTPUT
       - name: Build changelog for Release
+        if: steps.bump-version.outputs.bumped == 'true'
         env:
           NEW_VERSION: ${{ steps.bump-version.outputs.new_version }}
         run: |
           cz changelog --dry-run "${NEW_VERSION}" > .changelog.md
       - name: Release
+        if: steps.bump-version.outputs.bumped == 'true'
         env:
           GH_TOKEN: ${{ github.token }}
           NEW_VERSION_TAG: ${{ steps.bump-version.outputs.new_version_tag }}