Add avatars-gravatar plugin checker

Change-Id: Ia8dd086d29971893662bb28ed5e92c64f8b808ec
diff --git a/checkers.yaml b/checkers.yaml
index f262f93..aad5a75 100644
--- a/checkers.yaml
+++ b/checkers.yaml
@@ -106,6 +106,11 @@
     name: "Zuul Check Pipeline"
     description: "Run Zuul jobs on new patchsets"
 
+  - uuid: "zuul-check:plugins_avatars-gravatar"
+    repository: "plugins/avatars-gravatar"
+    name: "Zuul Check Pipeline"
+    description: "Run Zuul jobs on new patchsets"
+
   - uuid: "zuul-check:plugins_batch"
     repository: "plugins/batch"
     name: "Zuul Check Pipeline"
diff --git a/zuul/main.yaml b/zuul/main.yaml
index 49ce5cf..90b100b 100644
--- a/zuul/main.yaml
+++ b/zuul/main.yaml
@@ -33,6 +33,7 @@
           - plugins/admin-console
           - plugins/autosubmitter
           - plugins/avatars-external
+          - plugins/avatars-gravatar
           - plugins/batch
           - plugins/branch-network
           - plugins/changemessage