Set nightly-build pipeline as post-review

Change-Id: I30a4691853bff011992a54bd425f3c06fdb032c2
diff --git a/zuul.d/pipelines.yaml b/zuul.d/pipelines.yaml
index c0aeaa7..d975432 100644
--- a/zuul.d/pipelines.yaml
+++ b/zuul.d/pipelines.yaml
@@ -61,6 +61,7 @@
       Pipeline for nightly builds, executed everyday.
     manager: serial
     precedence: low
+    post-review: True
     trigger:
       timer:
         time: 2 0 * * *