feat: slack 40000 chars

Author: nevo-david

apps/frontend/src/components/new-launch/providers/slack/slack.provider.tsx

@@ -23,5 +23,5 @@ export default withProvider({
   CustomPreviewComponent: undefined,
   dto: SlackDto,
   checkValidity: undefined,
-  maximumCharacters: 280,
+  maximumCharacters: 400000,
 });