ci/gha: don't fail gh-pages update if nothing changed

And upload-artifact also needs to be updated to v3
to avoid deprecated features.

Author: TheOneric

.github/workflows/emscripten.yml

@@ -66,7 +66,7 @@ jobs:
         docker run --rm -v "${PWD}":/code -v "/tmp/emcc_lto:/emsdk/upstream/emscripten/cache/sysroot/lib/wasm32-emscripten/lto" libass/jso:latest
 
     - name: Upload Nightly Build
-      uses: actions/upload-artifact@v2
+      uses: actions/upload-artifact@v3
       if: (github.event_name == 'push' || github.event_name == 'workflow_dispatch') && github.ref == 'refs/heads/master'
       with:
         name: js
@@ -97,6 +97,7 @@ jobs:
           git config --global user.email "actions@noreply.github.com"
           git config --global user.name "GitHub Action"
           git add assets/js
-          git commit -m "$(printf \
-            "Update binaries to latest nightly\n\nFrom %s" "${{ github.sha }}")"
-          git push origin gh-pages
+          (git commit -m "$(printf \
+            "Update binaries to latest nightly\n\nFrom %s" "${{ github.sha }}")" \
+           && git push origin gh-pages) \
+           || : # Ignore if nothing changed