devShells/flora: update ghc to 9.10

nix/devShells/flora.nix

@@ -4,7 +4,7 @@
 let
   sources = import ../sources.nix;
 in
-  {pkgs ? import sources.nixpkgs-unstable {}}:
+  {pkgs ? import sources.pin-florashell {}}:
     pkgs.mkShell (let
       libs = with pkgs; [
         zlib
@@ -12,25 +12,24 @@ in
         libsodium
       ];
 
-      fourmolu = let
-        pkgs = import sources.pin-fourmolu {};
-      in
-        with pkgs; let
-          hlib = haskell.lib;
-          fourmolu = haskell.packages.ghc910.callHackage "fourmolu" "0.17.0.0" {};
-        in
-          hlib.dontCheck (hlib.doJailbreak fourmolu);
+      hlib = pkgs.haskell.lib;
+
+      callHackage = {name, version}:
+        let pkg = pkgs.haskell.packages.ghc910.callHackage name version {};
+         in hlib.dontCheck (hlib.doJailbreak pkg);
     in {
       name = "flora";
       packages = with pkgs;
-        [
-          haskellPackages.postgresql-migration
-          fourmolu
-          haskellPackages.hlint
-          haskellPackages.apply-refact
+      let
+        haskellPackages = haskell.packages.ghc910;
+      in
+        # These don't build directly and need to be pinned
+        map callHackage [
+          {name = "fourmolu"; version = "0.17.0.0";}
+          {name = "postgresql-migration"; version = "0.2.1.8";}
+        ]
+        ++ [
           haskellPackages.ghcid
-          haskellPackages.ghc-tags
-
           haskellPackages.cabal-fmt
           haskellPackages.cabal-install
           haskellPackages.ghc