Build Gerrit for stable-3.11 branches

Change-Id: I97af700fbf140f3b646ed3c20c6eab863f092d6a

zuul.d/project.yaml

diff --git a/zuul.d/project.yaml b/zuul.d/project.yaml
index 37c9a2e..f0e57dc 100644
--- a/zuul.d/project.yaml
+++ b/zuul.d/project.yaml
@@ -8,5 +8,6 @@
         - test-gerrit-build-stable-3.8
         - test-gerrit-build-stable-3.9
         - test-gerrit-build-stable-3.10
+        - test-gerrit-build-stable-3.11
         - test-gitiles-build-master
         - test-install-build-essential

zuul.d/test-jobs.yaml

diff --git a/zuul.d/test-jobs.yaml b/zuul.d/test-jobs.yaml
index b6a608f..c5a521a 100644
--- a/zuul.d/test-jobs.yaml
+++ b/zuul.d/test-jobs.yaml
@@ -80,6 +80,11 @@
     override-checkout: stable-3.10
 
 - job:
+    name: test-gerrit-build-stable-3.11
+    parent: test-gerrit-build-master
+    override-checkout: stable-3.11
+
+- job:
     name: test-gitiles-build-master
     parent: gitiles-build
     files: