Pin git to 1.14.0

Seems the latest release (1.17.2) breaks parsing in modulesync and
causes the following traceback.

/lib/modulesync/repository.rb:37:in `default_branch': undefined method
`[]' for nil:NilClass (NoMethodError)

Let's pin the package to workaround the problem until the issue is
fixed.

This makes the lint job non-voting until we merge [1], which requires
this pinning.

[1] https://review.opendev.org/876248

Change-Id: Ib6309ae8d13477eadcd4309d5be6bb7b170bfe4f

.zuul.yaml

@@ -1,3 +1,11 @@
 - project:
     templates:
       - puppet-openstack-library-jobs
+    check:
+      jobs:
+        - puppet-openstack-libraries-puppet-lint-ubuntu-jammy:
+            voting: false
+    gate:
+      jobs:
+        - puppet-openstack-libraries-puppet-lint-ubuntu-jammy:
+            voting: false

Gemfile

@@ -1,5 +1,6 @@
 source 'https://rubygems.org'
 
+gem 'git', '= 1.14.0'
 gem 'modulesync'
 gem 'json_pure'