Update README.md with new slack invitation link

Author: wing328

README.md

@@ -1,6 +1,6 @@
 # OpenApi Generator PIP Package Generator
 
-[![Join the Slack chat room](https://img.shields.io/badge/Slack-Join%20the%20chat%20room-orange)](https://join.slack.com/t/openapi-generator/shared_invite/enQtNzAyNDMyOTU0OTE1LTY5ZDBiNDI5NzI5ZjQ1Y2E5OWVjMjZkYzY1ZGM2MWQ4YWFjMzcyNDY5MGI4NjQxNDBiMTlmZTc5NjY2ZTQ5MGM)
+[![Join the Slack chat room](https://img.shields.io/badge/Slack-Join%20the%20chat%20room-orange)](https://join.slack.com/t/openapi-generator/shared_invite/zt-12jxxd7p2-XUeQM~4pzsU9x~eGLQqX2g)
 <a href="https://github.com/psf/black"><img alt="Code style: black" src="https://img.shields.io/badge/code%20style-black-000000.svg"></a>
 
 OpenAPI Generator allows generation of API client libraries (SDK generation), server stubs, documentation and