upgrade nix dependencies

This updates the flake and since we haven't hacked on this for ages
the overlays aren't needed any more since all of them are now
available as builds.

Author: romanofski

.github/workflows/haskell-ci.yml

@@ -1,6 +1,6 @@
 # This GitHub workflow config has been generated by a script via
 #
-#   haskell-ci '--haddock' '--apt' 'elinks tmux vim less notmuch libnotmuch-dev libtalloc-dev' '--github-patches' '.github/haskell-ci-github.patch' 'github' 'purebred.cabal'
+#   haskell-ci 'github' 'purebred.cabal' '--config' 'cabal.haskell-ci'
 #
 # To regenerate the script (for example after adjusting tested-with) run
 #
@@ -211,7 +211,7 @@ jobs:
           ${CABAL} -vnormal check
       - name: haddock
         run: |
-          $CABAL v2-haddock --disable-documentation --haddock-all $ARG_COMPILER --with-haddock $HADDOCK $ARG_TESTS $ARG_BENCH all
+          if [ $((HCNUMVER >= 90000)) -ne 0 ] ; then $CABAL v2-haddock --disable-documentation --haddock-all $ARG_COMPILER --with-haddock $HADDOCK $ARG_TESTS $ARG_BENCH all ; fi
       - name: unconstrained build
         run: |
           rm -f cabal.project.local

.nix/bimap.nix

@@ -1,21 +1,10 @@
 let
-  haskellCompilerVersion = "ghc924";
+  haskellCompilerVersion = "ghc910";
   haskellPackagesOverlay = self: super: with super.haskell.lib; {
     haskellPackages = super.haskell.packages.${haskellCompilerVersion}.override {
       overrides = hself: hsuper: {
         purebred = hsuper.callPackage ./purebred.nix { };
-        purebred-email = hsuper.callPackage ./purebred-email.nix { };
         purebred-icu = hsuper.callPackage ./purebred-icu.nix { };
-        brick = hsuper.callPackage ./brick.nix { };
-        text-zipper = hsuper.callPackage ./text-zipper.nix { };
-        bimap = hsuper.callPackage ./bimap.nix { };
-        vty = hsuper.callPackage ./vty.nix { };
-        vty-unix = hsuper.callPackage ./vty-unix.nix { };
-        vty-crossplatform = hsuper.callPackage ./vty-crossplatform.nix { };
-        notmuch = hsuper.callPackage ./hsnotmuch.nix {
-          notmuch = self.pkgs.notmuch;
-          talloc = self.pkgs.talloc;
-        };
       };
     };
     make-purebred-with-packages = with-icu: