agdaPackages.agda-categories: remove heap size increase

The maximum heap size was removed in Agda 2.6.4.2
https://github.com/agda/agda/issues/7070

pkgs/development/libraries/agda/agda-categories/default.nix

@@ -26,10 +26,6 @@ mkDerivation rec {
     find src -name '*.agda' | sed -e 's|^src/[/]*|import |' -e 's|/|.|g' -e 's/.agda//' -e '/import Everything/d' | LC_COLLATE='C' sort > Everything.agda
   '';
 
-  # agda: Heap exhausted;
-  # agda: Current maximum heap size is 4294967296 bytes (4096 MB).
-  GHCRTS = "-M5G";
-
   buildInputs = [ standard-library ];
 
   meta = with lib; {