Add irrelevant-files for grenade-py3 job

Adding irrelevant-files for new job grenade-py3 to avoid
running this integrated testing job on doc or unit test changes.

Change-Id: I2918b6563a65729e70323ca5986fc7a66e2bcc94
diff --git a/.zuul.yaml b/.zuul.yaml
index 9af79a6..42f2347 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -531,6 +531,8 @@
             irrelevant-files: *tempest-irrelevant-files
         - neutron-grenade:
             irrelevant-files: *tempest-irrelevant-files
+        - grenade-py3:
+            irrelevant-files: *tempest-irrelevant-files
         - devstack-plugin-ceph-tempest:
             voting: false
             irrelevant-files: *tempest-irrelevant-files
@@ -573,6 +575,8 @@
             irrelevant-files: *tempest-irrelevant-files
         - neutron-grenade:
             irrelevant-files: *tempest-irrelevant-files
+        - grenade-py3:
+            irrelevant-files: *tempest-irrelevant-files
     experimental:
       jobs:
         - tempest-cinder-v2-api: