Retire puppet-congress

Due to the retirement of congress project[1], puppet-congress will be
retired[2].

[1] https://review.opendev.org/#/c/721742/
[2] http://lists.openstack.org/pipermail/openstack-discuss/2020-June/015555.html

Depends-on: https://review.opendev.org/#/c/737144/
Change-Id: Ibebeec6695d31b174c9fca847f9a3b2e10322067

reference/legacy.yaml

@@ -1716,6 +1716,10 @@ Puppet OpenStack:
       repos:
         - openstack/puppet-crane
       retired-on: 2019-07-17
+    puppet-congress:
+      repos:
+        - openstack/puppet-congress
+      retired-on: 2020-06-21
 
 RefStack:
   ptl:

reference/projects.yaml

@@ -2327,9 +2327,6 @@ Puppet OpenStack:
     puppet-cloudkitty:
       repos:
         - openstack/puppet-cloudkitty
-    puppet-congress:
-      repos:
-        - openstack/puppet-congress
     puppet-designate:
       repos:
         - openstack/puppet-designate