Bump github/issue-metrics from 3.19.0 to 3.20.0

Bumps [github/issue-metrics](https://github.com/github/issue-metrics) from 3.19.0 to 3.20.0.
- [Release notes](https://github.com/github/issue-metrics/releases)
- [Commits](0bac475850...6a0f49b4e1)

---
updated-dependencies:
- dependency-name: github/issue-metrics
  dependency-version: 3.20.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/issue-metrics.yml

@@ -35,7 +35,7 @@ jobs:
         echo "last_month=$first_day..$last_day" >> "$GITHUB_ENV"
 
     - name: Run issue-metrics tool
-      uses: github/issue-metrics@0bac4758505aae5956ceaf77d747e65680bcafb0 # v3.19.0
+      uses: github/issue-metrics@6a0f49b4e14363b63e65ec698b43715b69d21f6d # v3.20.0
       env:
         GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         SEARCH_QUERY: 'repo:FreeCAD/FreeCAD is:issue created:${{ env.last_month }}'