cabal2nix: build with hpack 0.23

pkgs/development/haskell-modules/configuration-common.nix

···
   };
 
   # Need newer versions of their dependencies than the ones we have in LTS-10.x.
-  cabal2nix = super.cabal2nix.override { hpack = self.hpack_0_22_0; };
+  cabal2nix = super.cabal2nix.override { hpack = self.hpack_0_23_0; };
   hlint = super.hlint.overrideScope (self: super: { haskell-src-exts = self.haskell-src-exts_1_20_1; });
 
   # https://github.com/bos/configurator/issues/22

pkgs/development/haskell-modules/configuration-hackage2nix.yaml

···
   - haskell-gi-overloading == 0.0       # gi-* packages use this dependency to disable overloading support
   - haskell-src-exts == 1.19.*          # required by hindent and structured-haskell-mode
   - hoogle == 5.0.14                    # required by hie-hoogle
-  - hpack == 0.20.*                     # required by stack-1.6.1
   - inline-c < 0.6                      # required on GHC 8.0.x
   - inline-c-cpp < 0.2                  # required on GHC 8.0.x
   - language-c == 0.7.0                 # required by c2hs hack to work around https://github.com/haskell/c2hs/issues/192.