Adds publishing step to workflow

.github/workflows/nightly.yml

@@ -171,3 +171,26 @@ jobs:
         run: |
           cd clava/Clava-JS
           npm run test
+
+      # Only on ubuntu-latest
+      - name: Publish JS
+        if: matrix.os == 'ubuntu-latest' && matrix.node-version == '20.x'
+        run: | 
+            echo "Attempt to publish while running on {{ matrix.os }} and Node.js {matrix.node-version}"
+            if [[ "${{ github.event_name }}" == "push" ]]; then
+                if [ "${{ github.ref }}" == "refs/heads/staging" ]; then
+                    echo "Publishing from staging, creating timestamped prerelease and updating tag 'staging'"
+                    TIMESTAMP=$(date +"%Y%m%d%H%M%S")
+                    npm version prerelease --preid="$TIMESTAMP"
+                    npm publish --tag staging --access public
+                elif [ "${{ github.ref }}" == "refs/heads/master" ]; then
+                    echo "Publishing from main, incrementing patch version before publishing"
+                    npm version patch
+                    npm publish
+                    git push # Push updated version
+                fi
+            else
+                echo "Not a push event, skipping publish."
+            fi
+        env:
+          NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}