python3Packages.gst-python: fix darwin build

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

@@ -1,5 +1,6 @@
 {
   lib,
+  stdenv,
   buildPythonPackage,
   fetchurl,
   fetchpatch,
@@ -78,6 +79,10 @@ buildPythonPackage rec {
   # https://github.com/NixOS/nixpkgs/issues/47390
   installCheckPhase = "meson test --print-errorlogs";
 
+  preCheck = lib.optionalString stdenv.hostPlatform.isDarwin ''
+    export DYLD_LIBRARY_PATH="${gst_all_1.gst-plugins-base}/lib"
+  '';
+
   passthru = {
     updateScript = directoryListingUpdater { };
   };