chore: update community link

Author: yury-s

.github/ISSUE_TEMPLATE/config.yml

@@ -1,4 +1,4 @@
 contact_links:
-  - name: Join our Slack community
-    url: https://aka.ms/playwright-slack
-    about: Ask questions and discuss with other community members
+  - name: Join our Discord Server
+    url: https://aka.ms/playwright/discord
+    about: Ask questions and discuss with other community members