Skip functional tests for .pre-commit-config.yaml update

The file is used by only pep8 target.

Change-Id: I780c0cd18c6eee2cb98c38e069fe49a2c6988492
Signed-off-by: Takashi Kajinami <kajinamit@oss.nttdata.com>

.zuul.yaml

@@ -11,6 +11,7 @@
         heat: https://opendev.org/openstack/heat
     irrelevant-files:
       - ^\.gitreview$
+      - ^\.pre-commit-config\.yaml$
       - ^(test-|)requirements.txt$
       - ^setup.cfg$
       - ^doc/.*$