Tweak CI workflow

.github/workflows/go.yml

@@ -1,14 +1,13 @@
-# This workflow will build a golang project
-# For more information see: https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-go
-
 name: Go
 
 on:
   push:
-    branches: [ "main" ]
   pull_request:
     branches: [ "main" ]
 
+permissions:
+  content: read
+
 jobs:
 
   build: