Update publish action

Signed-off-by: Ben Sherman <[email protected]>

.github/workflows/publish.yml

@@ -1,4 +1,4 @@
-name: Deploy Extension
+name: Publish Extension
 
 on:
   workflow_dispatch:
@@ -28,6 +28,9 @@ jobs:
         env:
           VERSION: ${{ github.event.inputs.version }}
 
+      - name: Build vscode extension
+        run: ./gradlew build
+
       - name: Publish to Open VSX Registry
         uses: HaaLeo/publish-vscode-extension@v1
         with: