fix(ci): remove id-token:write from workflow-level permissions

Keep workflow-level permissions minimal; id-token:write is already
granted at the job level where it's needed.

Signed-off-by: Miguel Martinez Trivino <miguel@chainloop.dev>

Author: migmartri

.github/workflows/author_verification.yml

@@ -4,9 +4,7 @@ on:
   push:
     branches: ["main"]
 
-permissions:
-  contents: read
-  id-token: write # required for SLSA attestation
+permissions: read-all
 
 jobs:
   verify: