fix: replace the expired slack chat link

Signed-off-by: Jonathan Gonzalez V. <jonathan.abdiel@gmail.com>

Author: sxd

layouts/partials/nav.html

@@ -58,7 +58,7 @@
         <a class="github-button" href="https://github.com/cloudnative-pg/cloudnative-pg"
           data-color-scheme="no-preference: light; light: light; dark: dark;" data-size="large" data-show-count="true"
           aria-label="Star cloudnative-pg/cloudnative-pg on GitHub">Star</a>
-        <a href="https://join.slack.com/t/cloudnativepg/shared_invite/zt-237bhehx3-htDW2kz2hKJxEhn1W4VTnw">
+        <a href="https://join.slack.com/t/cloudnativepg/shared_invite/zt-2vedd06pe-vMZf4wJ3l_H_hB3YCZ947A">
           <img src="/icons/Slack.svg" alt="Slack" title="Join our Slack channel now!">
         </a>
         <a href="https://twitter.com/CloudNativePg">