Require review to run jobs, in order to use secrets

That's required to support e.g. Pulp secrets in stackhpc-kayobe-config
for now, until we get some proper infrastructure in place
(e.g. short-lived Ark/local SMS Pulp tokens or something similar)

Author: mnasiadka

zuul.d/pipelines.yaml

@@ -4,6 +4,7 @@
       Newly uploaded patchsets enter this pipeline to receive an
       initial check status.
     manager: independent
+    post-review: true
     trigger:
       github:
         # Run this pipeline on new/changed pull requests