utf8cpp: disable tests on darwin

Ever since the test framework was changed, tests started to fail on
Darwin due to an exception being thrown somewhere in the test framework
code. As this failure doesn't indicate a bug in utf8cpp, we can work
around this by disabling the test suite on darwin.

Closes #144265.
Reference https://github.com/nemtrif/utfcpp/issues/84.

pkgs/development/libraries/utf8cpp/default.nix

@@ -18,7 +18,9 @@ stdenv.mkDerivation rec {
 
   nativeBuildInputs = [ cmake ];
 
-  doCheck = true;
+  # Tests fail on darwin, probably due to a bug in the test framework:
+  # https://github.com/nemtrif/utfcpp/issues/84
+  doCheck = !stdenv.isDarwin;
 
   meta = with lib; {
     homepage = "https://github.com/nemtrif/utfcpp";