[Metal] Enable Metal 4 shader compilation

Use the latest SDK language version when available so generated MPP tensor_ops shaders can compile on M5+ while preserving the existing fallback for older SDKs.

Author: oraluben

src/runtime/metal/metal_module.mm

@@ -124,7 +124,11 @@ int GetPropertyMask() const final {
 
     if (fmt_ == "metal") {
       MTLCompileOptions* opts = [MTLCompileOptions alloc];
+#if defined(MTLLanguageVersion4_0)
+      opts.languageVersion = MTLLanguageVersion4_0;
+#else
       opts.languageVersion = MTLLanguageVersion2_3;
+#endif
       opts.fastMathEnabled = YES;
       // opts = nil;
       // Per-kernel payload is bytes; treat as UTF-8 MSL source.