Make windmill-src-ubuntu-bionic voting

Depends-On: https://review.opendev.org/c/zuul/nodepool/+/797740
Change-Id: If3cadb107ac7d2f9196322f077e60f1d255fb36e
Signed-off-by: Paul Belanger <pabelanger@redhat.com>

.zuul.d/project-templates.yaml

@@ -15,9 +15,9 @@
     check:
       jobs:
         - windmill-ubuntu-bionic
-        - windmill-src-ubuntu-bionic:
-            voting: false
+        - windmill-src-ubuntu-bionic
     gate:
       queue: windmill
       jobs:
         - windmill-ubuntu-bionic
+        - windmill-src-ubuntu-bionic