workflows: Fix permission setting on new MUSL job

I didn't realize I need to specify the permission setting on all
jobs in a workflow.

Reported-by: CodeQL
Signed-off-by: Chuck Lever <[email protected]>

Author: chucklever

.github/workflows/makefile.yml

@@ -45,6 +45,7 @@ jobs:
   build-musl:
 
     runs-on: ubuntu-latest
+    permissions: read-all
     container: alpine:latest
     strategy:
       fail-fast: false