Globally skip devstack job for pre-commit config update

pre-commit has been introduced to number of projects like oslo to run
lint checks such as hacking. The pre-commit config file does not affect
functionality, so devstack job is not needed when only the file is
updated.

Change-Id: I4294fe0c4df2c36c8575613b05a1f9c2eb745d18

.zuul.yaml

@@ -432,6 +432,8 @@
       - ^releasenotes/.*$
       # Translations
       - ^.*/locale/.*po$
+      # pre-commit config
+      - ^.pre-commit-config.yaml$
 
 - job:
     name: devstack-minimal