Nix: fix the duplicate

Author: deepfire

nix/.stack.nix/default.nix

@@ -26,7 +26,6 @@
         "micro-recursion-schemes" = (((hackage.micro-recursion-schemes)."5.0.2.2").revisions).default;
         "streaming-binary" = (((hackage.streaming-binary)."0.3.0.1").revisions).default;
         "cborg" = (((hackage.cborg)."0.2.2.0").revisions).default;
-        "canonical-json" = (((hackage.canonical-json)."0.6.0.0").revisions).default;
         "graphviz" = (((hackage.graphviz)."2999.20.0.3").revisions)."cde383c356bc41136ed53cd27e0800f46dbd2185600dd0de18d66d5c49739d94";
         "quickcheck-state-machine" = (((hackage.quickcheck-state-machine)."0.6.0").revisions)."3e4f8df0f6b5d415e3c8840dc75034a63e37f56f5f8cfa1035ded16345235ac4";
         cardano-byron-proxy = ./cardano-byron-proxy.nix;
@@ -96,4 +95,4 @@
       }
     ];
   compiler = "ghc-8.6.5";
-  }
+  }