Make tempest-full-py3 not run for unit tests change

This commit makes the tempest-full-py3 job not run for unit test
change because it's meaningless and it just consumes our gate machine
resources.

Change-Id: I4f3e40995e2719bc449621d3056b1a6142c1d48f
diff --git a/.zuul.yaml b/.zuul.yaml
index c5f7ecc..5f13438 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -385,6 +385,8 @@
               - ^tempest/tests/.*$
         - tempest-full-parallel:
             irrelevant-files: *tempest-irrelevant-files
+        - tempest-full-py3:
+            irrelevant-files: *tempest-irrelevant-files
         - tempest-full-py36:
             irrelevant-files: *tempest-irrelevant-files
         - tempest-full-rocky: