github: define alpine permissions [skip ci]

> unauthorized: access token has insufficient scopes

.github/workflows/alpine.yml

@@ -10,7 +10,9 @@ on:
 env:
   IMAGE_NAME: kamailio-ci
   SOURCE_BRANCH: ${{ github.ref_name }}
-
+permissions:
+  contents: read
+  packages: write 
 jobs:
   x86_64:
     runs-on: ubuntu-latest