haskell.compiler.ghc966: drop

Latest 9.6.x minor release is 9.6.7, which is also in Stackage 22.44.

Thus, dropping according to the GHC Deprecation Policy.

pkgs/development/compilers/ghc/9.6.6.nix

@@ -1,4 +0,0 @@
-import ./common-hadrian.nix {
-  version = "9.6.6";
-  sha256 = "008f7a04d89ad10baae6486c96645d7d726aaac7e1476199f6dd86c6bd9977ad";
-}

pkgs/top-level/haskell-packages.nix

@@ -198,24 +198,6 @@ in
         buildTargetLlvmPackages = pkgsBuildTarget.llvmPackages_15;
         llvmPackages = pkgs.llvmPackages_15;
       };
-      ghc966 = callPackage ../development/compilers/ghc/9.6.6.nix {
-        bootPkgs =
-          # For GHC 9.2 no armv7l bindists are available.
-          if stdenv.buildPlatform.isAarch32 then
-            bb.packages.ghc928
-          else if stdenv.buildPlatform.isPower64 && stdenv.buildPlatform.isLittleEndian then
-            bb.packages.ghc928
-          else
-            bb.packages.ghc924Binary;
-        inherit (buildPackages.python3Packages) sphinx;
-        # Need to use apple's patched xattr until
-        # https://github.com/xattr/xattr/issues/44 and
-        # https://github.com/xattr/xattr/issues/55 are solved.
-        inherit (buildPackages.darwin) xattr autoSignDarwinBinariesHook;
-        # Support range >= 11 && < 16
-        buildTargetLlvmPackages = pkgsBuildTarget.llvmPackages_15;
-        llvmPackages = pkgs.llvmPackages_15;
-      };
       ghc967 = callPackage ../development/compilers/ghc/9.6.7.nix {
         bootPkgs =
           # For GHC 9.2 no armv7l bindists are available.
@@ -519,11 +501,6 @@ in
         ghc = bh.compiler.ghc963;
         compilerConfig = callPackage ../development/haskell-modules/configuration-ghc-9.6.x.nix { };
       };
-      ghc966 = callPackage ../development/haskell-modules {
-        buildHaskellPackages = bh.packages.ghc966;
-        ghc = bh.compiler.ghc966;
-        compilerConfig = callPackage ../development/haskell-modules/configuration-ghc-9.6.x.nix { };
-      };
       ghc967 = callPackage ../development/haskell-modules {
         buildHaskellPackages = bh.packages.ghc967;
         ghc = bh.compiler.ghc967;

pkgs/top-level/release-haskell.nix

@@ -68,7 +68,6 @@ let
     ghc928
     ghc948
     ghc963
-    ghc966
     ghc967
     ghc981
     ghc982
@@ -640,7 +639,7 @@ let
       semaphore-compat = [
         # Compiler < 9.8 don't have the semaphore-compat core package, but
         # requires unix >= 2.8.1.0 which implies GHC >= 9.6 for us.
-        compilerNames.ghc966
+        compilerNames.ghc967
       ];
       weeder = lib.subtractLists [
         compilerNames.ghc9101