Revert "Update ghc-lib and ghc-lib-parser"

This reverts commit b43aa9b.

default.nix

@@ -13,21 +13,4 @@ let lib = nixpkgs.lib;
               [ "cabal.project.local" ".ghc.environment." ]
         ) src;
 
-    haskellPackages =
-      nixpkgs.haskellPackages.extend (super: self:
-      {
-        ghc-lib = self.callHackageDirect {
-          pkg = "ghc-lib";
-          ver = "8.10.2.20200916";
-          sha256 = "1gx0ijay9chachmd1fbb61md3zlvj24kk63fk3dssx8r9c2yp493";
-        } {};
-
-        ghc-lib-parser = self.callHackageDirect {
-          pkg = "ghc-lib-parser";
-          ver = "8.10.2.20200916";
-          sha256 = "1apm9zn484sm6b8flbh6a2kqnv1wjan4l58b81cic5fc1jsqnyjk";
-        } {};
-
-      });
-
-in haskellPackages.callCabal2nix "circuit-notation" (filterHaskellSource ./.) {}
+in nixpkgs.haskellPackages.callCabal2nix "circuit-notation" (filterHaskellSource ./.) {}