chore: fix slack channel link (#1177)

Author: Shreya

README.md

@@ -87,7 +87,7 @@ Read the [SAM Documentation Contribution Guide](https://github.com/awsdocs/aws-s
 started. 
 
 ### Join the SAM Community on Slack
-[Join the SAM developers channel (#samdev)](https://join.slack.com/t/awsdevelopers/shared_invite/enQtMzg3NTc5OTM2MzcxLTdjYTdhYWE3OTQyYTU4Njk1ZWY4Y2ZjYjBhMTUxNGYzNDg5MWQ1ZTc5MTRlOGY0OTI4NTdlZTMwNmI5YTgwOGM/) on Slack to collaborate with fellow community members and the AWS SAM team.
+[Join the SAM developers channel (#samdev)](https://join.slack.com/t/awsdevelopers/shared_invite/enQtMzg3NTc5OTM2MzcxLTIxNjc0ZTJkNmYyNWY3OWE4NTFiNzU1ZTM2Y2VkNmFlNjQ2YjI3YTE1ZDA5YjE5NDE2MjVmYWFlYWIxNjE2NjU) on Slack to collaborate with fellow community members and the AWS SAM team.