maintainers/team-list: Enable feature freeze ping for gcc

Since `gcc` is listed as [release critical package], it might make sense
to have the team included in the feature freeze ping.

[release critical package]: https://nixos.github.io/release-wiki/Release-Critical-Packages.html

maintainers/team-list.nix

@@ -299,6 +299,7 @@ with lib.maintainers;
     ];
     scope = "Maintain GCC (GNU Compiler Collection) compilers";
     shortName = "GCC";
+    enableFeatureFreezePing = true;
   };
 
   geospatial = {