neutron-lib: Skip tempest job for changes in unit tests code

... because any change in unit tests code does never affect
functionality.

Change-Id: Ic4f54fed3ed1e0acf4132cad9ffba2dcede72372
diff --git a/zuul.d/master_jobs.yaml b/zuul.d/master_jobs.yaml
index 64283b5..18bc638 100644
--- a/zuul.d/master_jobs.yaml
+++ b/zuul.d/master_jobs.yaml
@@ -120,6 +120,7 @@
       - ^tox.ini$
       - ^neutron/agent/.*$
       - ^neutron/privileged/.*$
+      - ^neutron_lib/tests/unit/.*$
       - ^neutron_tempest_plugin/scenario/.*$