python3Packages.vispy: skip patch on Darwin

The upstream code can already successfully find the system framework
on macOS, and fontconfig isn’t used at all.

Co-authored-by: Randy Eckenrode <randy@largeandhighquality.com>

pkgs/development/python-modules/vispy/default.nix

@@ -31,7 +31,7 @@ buildPythonPackage rec {
     hash = "sha256-7ti0TW9ch70pWySqmi4OTm3GqQXM7gGy1ByPvwp2ez0=";
   };
 
-  patches = [
+  patches = lib.optionals (!stdenv.hostPlatform.isDarwin) [
     (substituteAll {
       src = ./library-paths.patch;
       fontconfig = "${fontconfig.lib}/lib/libfontconfig${stdenv.hostPlatform.extensions.sharedLibrary}";