Try using .dylib suffix on macs.

Author: adalisk-emikhaylov

source/non_limited_api/non_limited_api_stubs.cpp

@@ -6,8 +6,13 @@
 #define PYBIND11_NONLIMITEDAPI_DLOPEN(dir, file) LoadLibraryW((dir + std::wstring(file.begin(), file.end()) + L".dll").c_str())
 #define PYBIND11_NONLIMITEDAPI_DLOPEN_ERROR std::to_string(GetLastError()).c_str()
 #else
+#ifdef __APPLE__
+#define PYBIND11_NONLIMITEDAPI_SHLIB_SUFFIX ".dylib"
+#else
+#define PYBIND11_NONLIMITEDAPI_SHLIB_SUFFIX ".so"
+#endif
 #include <dlfcn.h> // For `dlopen` and friends.
-#define PYBIND11_NONLIMITEDAPI_DLOPEN(dir, file) dlopen((dir + "lib" + file + ".so").c_str(), RTLD_NOW | RTLD_GLOBAL)
+#define PYBIND11_NONLIMITEDAPI_DLOPEN(dir, file) dlopen((dir + "lib" + file + PYBIND11_NONLIMITEDAPI_SHLIB_SUFFIX).c_str(), RTLD_NOW | RTLD_GLOBAL)
 #define PYBIND11_NONLIMITEDAPI_DLOPEN_ERROR dlerror()
 #endif