CI: Skip dependabot PR branches. (#32006)

Also, reword Node.js setup step

.github/workflows/browserstack.yml

@@ -1,5 +1,8 @@
 name: BrowserStack
-on: [push]
+
+on:
+  push:
+
 env:
   CI: true
   NODE: 12.x
@@ -13,7 +16,7 @@ jobs:
       - name: Clone repository
         uses: actions/checkout@v2
 
-      - name: Set Node.js version
+      - name: Set up Node.js
         uses: actions/setup-node@v1
         with:
           node-version: "${{ env.NODE }}"