bump gradle to 6.5 (#29043)

Summary:
Bump Gradle to 6.5 or latest version.

## Changelog

[Android] [Changed] - bump Gradle to 6.5
Pull Request resolved: https://github.com/facebook/react-native/pull/29043

Test Plan: RNTester builds and run as expected

Reviewed By: JoshuaGross

Differential Revision: D22337424

Pulled By: mdvacca

fbshipit-source-id: 4d089a5edfac6672276572fae2a1a7a236142985