ci: adjusting pipeline

Author: nexus49

.github/workflows/pipeline.yaml

@@ -1,5 +1,11 @@
 name: pipe
-on: [push]
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
 
 concurrency:
   group: ${{ github.ref }}