knot-resolver: skip tests on aarch64-darwin (for now)

It used to build in a previous iteration
https://hydra.nixos.org/job/nixpkgs/aarch64-darwin/knot-resolver.aarch64-darwin
so I expect it will work without these tests
(I have no access to a darwin machine).

pkgs/servers/dns/knot-resolver/default.nix

@@ -79,7 +79,8 @@ unwrapped = stdenv.mkDerivation rec {
     rm -r "$out"/lib/sysusers.d/ # ATM more likely to harm than help
   '';
 
-  doInstallCheck = with stdenv; hostPlatform == buildPlatform;
+  doInstallCheck = with stdenv; hostPlatform == buildPlatform
+    && !(isDarwin && isAarch64); # avoid luarocks, as it's broken ATM on the platform
   installCheckInputs = [ cmocka which cacert lua.cqueues lua.basexx lua.http ];
   installCheckPhase = ''
     meson test --print-errorlogs