Update GitHub Actions workflows. (#739)

This PR was automatically generated by the
update-workflows-ecosystem-providers workflow in the pulumi/ci-mgmt
repo, from commit 4a65e6eff3992cd55e1328a125702b1e7d18eb13.

.github/workflows/publish.yml

@@ -80,10 +80,12 @@ jobs:
       shell: bash
       run: |
         # Get latest stable release. Return only first column from result (tag).
-        LAST_VERSION=$(gh release view --repo pulumi/pulumi-github --json tagName -q .tagName)
+        LAST_VERSION=$(gh release view --repo pulumi/pulumi-github --json tagName -q .tagName || echo "No stable release" )
         {
           echo 'summary<<EOF'
-          schema-tools compare --provider="github" --old-commit="$LAST_VERSION" --new-commit="--local-path=provider/cmd/pulumi-resource-github/schema.json"
+          if [[ "$LAST_VERSION" != "No stable release" ]]; then
+            schema-tools compare --provider="github" --old-commit="$LAST_VERSION" --new-commit="--local-path=provider/cmd/pulumi-resource-github/schema.json"
+          fi
           echo 'EOF'
         } >> "$GITHUB_OUTPUT"
     - name: Upload Provider Binaries