Update publishing workflow

Author: Stefterv

.github/workflows/release.yml

@@ -94,4 +94,8 @@ jobs:
         env:
           VSCE_PAT: ${{ secrets.VSCE_PAT }}
         run: |
-          vsce publish
+          vsce publish
+
+      - name: Publish to Open VSX
+        run: |
+          npx ovsx publish processing-vscode-extension-${{ github.event.release.tag_name }}.vsix -p ${{ secrets.OPENVSX_TOKEN }}