ci/release: append sponsorship details to release notes

Don't add to changelog as we don't want it repeated in CHANGELOG.md
but do add to release notes on GitHub which are just published.

Author: abhinav

.github/workflows/publish-release.yml

@@ -58,8 +58,15 @@ jobs:
 
     - name: Extract changelog
       run: |
-        tail -n+2 .changes/v${{ env.VERSION }}.md \
-          | tee ${{ github.workspace }}-CHANGELOG.txt
+        {
+          tail -n+2 .changes/v${{ env.VERSION }}.md 
+
+          # Add sponsorship info
+          echo ""
+          echo "---"
+          echo ""
+          echo "[Support git-spice development](https://github.com/sponsors/abhinav)"
+        } > ${{ github.workspace }}-CHANGELOG.txt
 
     - name: Tag a release
       if: inputs.skip_publish == false