Update main.yml

Made it so it only deploys pushes on the main branch

Author: skymen

.github/workflows/main.yml

@@ -1,7 +1,13 @@
 # This is a basic workflow to help you get started with Actions
 
 name: Build Vue
-on: [push]
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
 jobs:
   build_vue:
     runs-on: ubuntu-latest