Revert "Revert "Fix mkTf2Config derivation names ending with a dash -""

This reverts commit 98673e8d34.

tf2/packages/maps/jump-academy/default.nix

@@ -6,6 +6,7 @@ builtins.mapAttrs
     env.description = e.description;
     maps = [
       (fetchurl {
+        name = "${name}-src";
         inherit (e.src) url hash;
       })
     ];