docs: update Slack channel invite (cloudnative-pg#7019)

Closes cloudnative-pg#7018

Signed-off-by: Gabriele Bartolini <gabriele.bartolini@enterprisedb.com>

Author: gbartolini

.github/ISSUE_TEMPLATE/config.yml

@@ -4,5 +4,5 @@ contact_links:
     url: https://github.com/cloudnative-pg/cloudnative-pg/discussions
     about: Please ask and answer questions here.
   - name: Slack chat
-    url: https://join.slack.com/t/cloudnativepg/shared_invite/zt-2vedd06pe-vMZf4wJ3l_H_hB3YCZ947A
+    url: https://github.com/cloudnative-pg/cloudnative-pg?tab=readme-ov-file#communications
     about: Please join the slack channel and interact with our community

CONTRIBUTING.md

@@ -40,8 +40,7 @@ For development contributions, please refer to the separate section called
 ## Ask for Help
 
 The best way to reach us with a question when contributing is to drop a line in
-our [Slack channel](https://join.slack.com/t/cloudnativepg/shared_invite/zt-2vedd06pe-vMZf4wJ3l_H_hB3YCZ947A), or
-start a new Github discussion.
+our [Slack channel](README.md#communications), or start a new Github discussion.
 
 ## Raising Issues
 

README.md

@@ -114,7 +114,7 @@ MariaDB cluster).
 
 ## Communications
 
-- [Slack Channel](https://join.slack.com/t/cloudnativepg/shared_invite/zt-2vedd06pe-vMZf4wJ3l_H_hB3YCZ947A)
+- [Slack Channel](https://join.slack.com/t/cloudnativepg/shared_invite/zt-30a6l6bp3-u1lNAmh~N02Cfiv2utKTFg)
 - [Github Discussions](https://github.com/cloudnative-pg/cloudnative-pg/discussions)
 - [Twitter](https://twitter.com/CloudNativePg)