README: update slack join link

README.md

@@ -3,7 +3,7 @@
 [![rtx-3090 tests](https://github.com/hpcgroup/axonn/actions/workflows/nvidia-tests.yaml/badge.svg)](https://github.com/hpcgroup/axonn/actions/workflows/nvidia-tests.yaml)
 [![docs](https://readthedocs.org/projects/axonn/badge/?version=latest)](https://axonn.readthedocs.io/en/latest/?badge=latest)
 [![Code Style: Black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black)
-[![Join slack](https://img.shields.io/badge/slack-axonn--users-blue)](https://join.slack.com/t/axonn-users/shared_invite/zt-1vw4fm25c-XAH9n9d_3hg5TuHMw_7Ggw)
+[![Join slack](https://img.shields.io/badge/slack-axonn--users-blue)](https://join.slack.com/t/axonn-users/shared_invite/zt-2itbahk29-_Ig1JasFxnuVyfMtcC4GnA)
 
 AxoNN is a parallel framework for training deep neural networks.