Update dependencies

[thewheat]

Updating this dependency looks to fix the previous publishing issue due to existing tags.
Gradle-git is no longer in development so moving to new core library which is https://github.com/ajoberstar/gradle-git

Using older version of this dependency

• due to the fact that it requires Java 8 / 1.8 https://github.com/ajoberstar/grgit/releases/tag/2.0.0
• while our sourceCompatibility and targetCompatibility is set to 1.7 i.e. Java 7

  intercom-java/build.gradle

  Lines 41 to 42 in a0bc709

  	sourceCompatibility = 1.7
  	targetCompatibility = 1.7

[choran]

👍