`wxGTK30` has been removed from nixpkgs

[Anomalocaridid]

When I tried to install slippi-netplay from this flake's overlay, I got the following error:

error:
       … while calling the 'head' builtin

         at /nix/store/vby8c3909sglr03fxkclkly29vs49ncy-source/lib/attrsets.nix:784:11:

          783|         || pred here (elemAt values 1) (head values) then
          784|           head values
             |           ^
          785|         else

       … while evaluating the attribute 'value'

         at /nix/store/vby8c3909sglr03fxkclkly29vs49ncy-source/lib/modules.nix:759:9:

          758|     in warnDeprecation opt //
          759|       { value = builtins.addErrorContext "while evaluating the option `${showOption loc}':" value;
             |         ^
          760|         inherit (res.defsFinal') highestPrio;

       (stack trace truncated; use '--show-trace' to show the full trace)

       error: wxGTK30 has been removed from nixpkgs as it has reached end of life

It looks like slippi-netplay's dependency on the removed wxGTK30 package is preventing it from being built.