.github: restrict permissions

Author: tamird

.github/workflows/ci.yml

@@ -11,6 +11,8 @@ on:
 env:
   CARGO_TERM_COLOR: always
 
+permissions: {}
+
 jobs:
   llvm:
     uses: ./.github/workflows/llvm.yml

.github/workflows/llvm.yml

@@ -6,6 +6,8 @@ on:
       cache-key:
         value: ${{ jobs.llvm.outputs.cache-key }}
 
+permissions: {}
+
 jobs:
   llvm:
     runs-on: ubuntu-22.04

.github/workflows/release.yml

@@ -4,6 +4,8 @@ on:
   release:
     types: [published]
 
+permissions: {}
+
 jobs:
   llvm:
     uses: ./.github/workflows/llvm.yml