group normalization layer test (#766)
group normalization layer test (#766)

* init testing

* use np assert_allclose

* add no center and scale test

* sanitycheck

* add test

* revise based on comments

* add random seed

Co-authored-by: Gabriel de Marmiesse <40cb226a9ebd341312f9a230785978fcc568e9b6@gmail.com>

tensorflow/addons,tensorflow/addons,tensorflow/addons