publishing: Drop 'go' field from 'controller-manager' 'master' branch

This was previous incorrectly set to go1.13.
Dropping the field allows us to pick up the 'default-go-version'.

Signed-off-by: Stephen Augustus <saugustus@vmware.com>

staging/publishing/rules.yaml

@@ -1640,7 +1640,6 @@ rules:
       branch: master
       dir: staging/src/k8s.io/controller-manager
     name: master
-    go: 1.13.15
   - source:
       branch: release-1.19
       dir: staging/src/k8s.io/controller-manager