python3.pkgs.pysls: Fix build on Darwin

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

@@ -3,6 +3,7 @@
   liblsl,
   fetchFromGitHub,
   buildPythonPackage,
+  stdenv,
   numpy,
   setuptools,
   setuptools-scm,
@@ -23,7 +24,9 @@ buildPythonPackage rec {
 
   postPatch = ''
     substituteInPlace src/pylsl/lib/__init__.py \
-      --replace "def find_liblsl_libraries(verbose=False):" "$(echo -e "def find_liblsl_libraries(verbose=False):\n    yield '${liblsl}/lib/liblsl.so'")"
+      --replace "def find_liblsl_libraries(verbose=False):" "$(echo -e "def find_liblsl_libraries(verbose=False):\n    yield '${liblsl}/lib/liblsl.${
+        if stdenv.hostPlatform.isDarwin then "dylib" else "so"
+      }'")"
   '';
 
   build-system = [