Run gitlint with tox

Verification of git message is failing because of a pip installation
issue:
jorisroovers/gitlint#535
pypa/pip#12372

The issue has been addressed for pip v23.3.2:
https://github.com/pypa/pip/releases/tag/23.3.2

but the virtual environment for the pre-commit hook does not appear to
have the version available yet.

Run the gitlint with tox directly until the issue is resolved in the
Jenkins environment.

Change-Id: I033240f8f7bb5a14217dbc763687ac490ae4b3d0
Signed-off-by: Sangwook Ha <sangwook.ha@verizon.com>

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 minversion = 1.6.0
-envlist = docs,pre-commit
+envlist = docs,pre-commit,gitlint
 # TODO: Include docs when it starts performing strict checks.
 skipsdist = true
 
@@ -36,7 +36,9 @@ deps = pre-commit
 passenv = HOME
 commands =
     pre-commit run --all-files --show-diff-on-failure
-    pre-commit run gitlint-ci --hook-stage manual
+# FIXME: run gitlint with pre-commit once the following installation issue is resolved
+#        in the Jenkins environment: https://github.com/jorisroovers/gitlint/issues/535
+#    pre-commit run gitlint-ci --hook-stage manual
 
 [testenv:gitlint]
 basepython = python3