Removing research/community models

Update requirements.txt

Removing research/community models

Removing research/community models

Update release scripts

Fix typing deps==3.7.4.1

Revert keras imagenet benchmark to use old resnet cfit

Removing research/samples/tutorials models

Removing tutorials models

Revert "tf_upgrade_v2 on resnet and utils folders. (tensorflow#6154)" (…

…tensorflow#6162)

This reverts commit d6b2b83.