fix(cerbos): align .cerbos-hub.yaml with documented schema

Author: jonphipps

.cerbos-hub.yaml

@@ -2,9 +2,6 @@
 # This connects the repository to Cerbos Hub for GitOps policy management
 ---
 apiVersion: api.cerbos.cloud/v1
-source:
-  git:
-    workDir: cerbos
 labels:
   latest:         # 'latest' label pointing to the HEAD of the main branch
     branch: main