ci: refactor workflow permissions and triggers (#88)

Author: ReenigneArcher

.github/workflows/ci.yml

@@ -1,16 +1,9 @@
 ---
 name: CI
-permissions:
-  contents: read
+permissions: {}
 
 on:
   pull_request:
-    branches:
-      - master
-    types:
-      - opened
-      - synchronize
-      - reopened
   push:
     branches:
       - master
@@ -25,6 +18,8 @@ jobs:
     defaults:
       run:
         shell: ${{ matrix.shell }}
+    permissions:
+      contents: read
     runs-on: ${{ matrix.os }}
     strategy:
       fail-fast: false