trivial: Don't run integration tests on tools/.* updates

This adds an entry to irrelevant-files to skip running integration
tests following changes to files under tools/.* because nothing
under there effects integration tests.

Change-Id: I3235ef51defb9d70dec564bdfa63dca6264c0d63
diff --git a/.zuul.yaml b/.zuul.yaml
index 6b546ec..f061b12 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -477,6 +477,7 @@
               - ^setup.cfg$
               - ^tempest/hacking/.*$
               - ^tempest/tests/.*$
+              - ^tools/.*$
         - tempest-full-parallel:
             irrelevant-files: *tempest-irrelevant-files
         - tempest-full-py3: