chore(ci): restrict token permissions (#7470)

Replace read-all with contents:read and add explicit permissions to
follow principle of least privilege.

Signed-off-by: Ville Vesilehto <ville@vesilehto.fi>

.github/workflows/golangci-lint.yml

@@ -1,6 +1,11 @@
 name: golangci-lint
+
 on:
   pull_request:
+
+permissions:
+  contents: read
+
 jobs:
   golangci:
     name: lint