Update Exception Handling with exnref in Safari TP (#403)

Release notes
https://webkit.org/blog/15999/release-notes-for-safari-technology-preview-205/

I've tested it `wasm-feature-detect` on
https://webassembly.org/features/ as well

features.json

@@ -213,6 +213,7 @@
 				"branchHinting": "16",
 				"bulkMemory": "15",
 				"customAnnotationSyntaxInTheTextFormat": null,
+				"exceptionsFinal": ["flag", "Supported in Safari Technology Preview 205"],
 				"exceptions": "15.2",
 				"extendedConst": "17.4",
 				"gc": ["flag", "Supported in Safari Technology Preview 202"],