[StepSecurity] ci: Harden GitHub Actions

Signed-off-by: StepSecurity Bot <[email protected]>

Author: step-security-bot

.github/workflows/build.yml

@@ -23,6 +23,9 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
   cancel-in-progress: true
 
+permissions:
+  contents: read
+
 jobs:
   build:  
     runs-on: ubuntu-22.04