[Glitch] Enable ESLint no-useless-escape

Port db2c58d47a to glitch-soc

Signed-off-by: Claire <claire.github-309c@sitedethib.com>

app/javascript/flavours/glitch/features/compose/containers/warning_container.js

@@ -25,7 +25,7 @@ const buildHashtagRE = () => {
       '))', 'iu',
     );
   } catch {
-    return /(?:^|[^\/\)\w])#(\w*[a-zA-Z·]\w*)/i;
+    return /(?:^|[^/)\w])#(\w*[a-zA-Z·]\w*)/i;
   }
 };