Upgraded minimum Git version to 2.18.0

changelogs/unreleased/fj-47494-upgrade-git-to-2-18-0.yml

+---
+title: Upgrade minimum required Git version to 2.18.0
+merge_request: 22803
+author:
+type: other

doc/install/installation.md

@@ -79,7 +79,7 @@ Make sure you have the right version of Git installed
     # Install Git
     sudo apt-get install -y git-core
 
-    # Make sure Git is version 2.9.5 or higher
+    # Make sure Git is version 2.18.0 or higher
     git --version
 
 Is the system packaged Git too old? Remove it and compile from source.

lib/system_check/app/git_version_check.rb

@@ -7,7 +7,7 @@ module SystemCheck
       set_check_pass -> { "yes (#{self.current_version})" }
 
       def self.required_version
-        @required_version ||= Gitlab::VersionInfo.new(2, 9, 5)
+        @required_version ||= Gitlab::VersionInfo.parse('2.18.0')
       end
 
       def self.current_version