Stop publishing Git Version plugin

For now, the Git Version part of GradleUtils can stay contained within
GU itself until 3.0. When Git Version's Gradle plugin is split off into
MinecraftForge/GitVersion, it will probably start from version 3.0
itself to accommodate for the fact that there are already versions 2.4.x
of it.

Author: Jonathing

build_shared.gradle

@@ -40,13 +40,6 @@ gradlePlugin {
             description = 'Small collection of utilities for standardizing our gradle scripts'
             tags.set(['minecraftforge'])
         }
-        gitversion {
-            id = 'net.minecraftforge.gitversion'
-            implementationClass = 'net.minecraftforge.gradleutils.gitversion.GitVersionPlugin'
-            displayName = 'Git Version'
-            description = 'Provides versioning information based on git history and configurable subprojects'
-            tags.set(['git', 'version'])
-        }
         changelog {
             id = 'net.minecraftforge.changelog'
             implementationClass = 'net.minecraftforge.gradleutils.changelog.ChangelogPlugin'