⬆️ github-actions: Bump microsoft/PR-Metrics from 1.6.3 to 1.6.4

Bumps [microsoft/PR-Metrics](https://github.com/microsoft/pr-metrics) from 1.6.3 to 1.6.4.
- [Release notes](https://github.com/microsoft/pr-metrics/releases)
- [Commits](microsoft/PR-Metrics@v1.6.3...v1.6.4)

---
updated-dependencies:
- dependency-name: microsoft/PR-Metrics
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/pr-metrics.yml

@@ -22,7 +22,7 @@ jobs:
         with:
           fetch-depth: 0
 
-      - uses: microsoft/[email protected].3
+      - uses: microsoft/[email protected].4
         name: PR Metrics
         env:
           PR_METRICS_ACCESS_TOKEN: ${{ secrets.GITHUB_TOKEN }}