Update Safari support for Math.sumPrecise()

Safari has supported `Math.sumPrecise()` since Safari 18.4.

Author: jdatapple

javascript/builtins/Math.json

@@ -2107,7 +2107,7 @@
               "opera": "mirror",
               "opera_android": "mirror",
               "safari": {
-                "version_added": "preview"
+                "version_added": "18.4"
               },
               "safari_ios": "mirror",
               "samsunginternet_android": "mirror",