fix(ci): configure git identity before creating release tags

git tag -a creates an annotated tag, which requires a tagger identity.
The create-tag job runs on a bare runner checkout with no git config,
so it failed with "Committer identity unknown" across all 32 publish
workflows added by f0258c9336.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.github/workflows/publish-openbb-index.yml

@@ -133,6 +133,8 @@ jobs:
 
       - name: Create and push release tag
         run: |
+          git config user.name "github-actions[bot]"
+          git config user.email "github-actions[bot]@users.noreply.github.com"
           TAG="${PACKAGE}-v${VERSION}"
           git tag -a "$TAG" "$RELEASE_SHA" -m "${PACKAGE} ${VERSION}"
           git push origin "refs/tags/${TAG}"