Added jitpack repository to template (#25987)

Summary:
This PR will eliminate additional manual installation step for third-party RN libraries that include jitpack-published dependencies.

## Changelog

[Android] [Added] - Added jitpack repository to template
Pull Request resolved: https://github.com/facebook/react-native/pull/25987

Test Plan: No testing required.

Differential Revision: D16763401

Pulled By: cpojer

fbshipit-source-id: 72ff0146bd20c61a27b244f2dc7fea50781a4d1a

template/android/build.gradle

@@ -33,5 +33,6 @@ allprojects {
 
         google()
         jcenter()
+        maven { url 'https://jitpack.io' }
     }
 }