Remove expired Slack invite from README (#266)

Co-authored-by: Mirochill <200482516+Mirochill@users.noreply.github.com>

Author: Mirochill

README.md

@@ -24,7 +24,6 @@ There are 4 main components of Deequ, and they are:
 - With PyDeequ v0.1.8+, we now officially support Spark3 ! Just make sure you have an environment variable `SPARK_VERSION` to specify your Spark version! 
 - We've release a blogpost on integrating PyDeequ onto AWS leveraging services such as AWS Glue, Athena, and SageMaker! Check it out: [Monitor data quality in your data lake using PyDeequ and AWS Glue](https://aws.amazon.com/blogs/big-data/monitor-data-quality-in-your-data-lake-using-pydeequ-and-aws-glue/).
 - Check out the [PyDeequ Release Announcement Blogpost](https://aws.amazon.com/blogs/big-data/testing-data-quality-at-scale-with-pydeequ/) with a tutorial walkthrough the Amazon Reviews dataset!
-- Join the PyDeequ community on [PyDeequ Slack](https://join.slack.com/t/pydeequ/shared_invite/zt-te6bntpu-yaqPy7bhiN8Lu0NxpZs47Q) to chat with the devs!
 
 ## Quickstart