tools: allow the travis commit message job to fail

Travis often fails due to a commit message that does not adhere to
the commit guidelines. We are able to fix the commit message while
landing and it often confuses new contributors that travis fails.
Keeping the check in place but allowing a test failure to report
success should be a good middle ground.

PR-URL: #31116
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: David Carlier <devnexen@gmail.com>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

.travis.yml

@@ -88,3 +88,4 @@ jobs:
         - flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
   allow_failures:  # TODO (cclauss): remove this when dependencies are clean
     - name: "Find syntax errors in our Python dependencies"
+    - name: "First commit message adheres to guidelines at <a href=\"https://goo.gl/p2fr5Q\">https://goo.gl/p2fr5Q</a>"