remove Mac-incompatible Nix Flake dependency

Squashed commit of the following:

commit ab42f6c
Author: Peter Becich <peterbecich@gmail.com>
Date:   Fri Aug 25 23:25:03 2023 -0700

    `nix flake check` should succeed

commit 112b5d9
Author: Peter Becich <peterbecich@gmail.com>
Date:   Fri Aug 25 23:12:08 2023 -0700

    remove other dev shell dependencies

commit c24534c
Author: Peter Becich <peterbecich@gmail.com>
Date:   Fri Aug 25 23:00:51 2023 -0700

    remove pkg-config

commit bf4c400
Author: Peter Becich <peterbecich@gmail.com>
Date:   Fri Aug 25 22:50:44 2023 -0700

    try to fix `nix develop` on Mac

    #1247

Author: peterbecich

.github/workflows/nix-flake.yml

@@ -30,6 +30,5 @@ jobs:
         authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
     - run: nix build
 
-    # allow error until Flake check is improved
-    - continue-on-error: true
+    - continue-on-error: false
       run: nix flake check

flake.nix

@@ -40,10 +40,10 @@
 
                 # https://github.com/haskell/hackage-server/pull/1219#issuecomment-1597140858
                 # glibc
-                # icu67
-                # zlib
+                icu67
+                zlib
                 openssl
-                cryptodev
+                # cryptodev
                 pkg-config
                 brotli