ci: add permissions and concurrency to GitHub Actions workflows

- Add contents: read permission to benchmark.yml and sanitizers.yml
- Add concurrency configuration to prevent redundant workflow runs
- Improve CI security and resource efficiency

Author: LessUp

.github/workflows/benchmark.yml

@@ -6,6 +6,13 @@ on:
   pull_request:
     branches: [ main ]
 
+permissions:
+  contents: read
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 env:
   BUILD_TYPE: Release
 

.github/workflows/sanitizers.yml

@@ -6,6 +6,13 @@ on:
   pull_request:
     branches: [ main ]
 
+permissions:
+  contents: read
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   asan:
     name: AddressSanitizer