updated slack link

Signed-off-by: Sylvain Hellegouarch <sh@defuze.org>

Author: Lawouach

sources/reference/contributing.md

@@ -3,7 +3,7 @@ community-driven [set of projects](https://github.com/chaostoolkit). The
 community's input is what makes this project special and a success. 
 
 Your input could take the form of ***raising issues***, ***voting for issues***, 
-***starring projects***, ***joining us on our [community Slack team](https://join.slack.com/t/chaostoolkit/shared_invite/zt-22c5isqi9-3YjYzucVTNFFVIG~Kzns8g)***, ***submitting pull requests***, or even ***suggesting whole new extension projects***.
+***starring projects***, ***joining us on our [community Slack team](https://join.slack.com/t/chaostoolkit/shared_invite/zt-38fubgbc2-Ui3vgrbiS9xq8rnICqNv_Q)***, ***submitting pull requests***, or even ***suggesting whole new extension projects***.
 
 Whatever you can contribute, ***we're listening and want you to help us drive the 
 project forward***.