Update package.json

package.json

@@ -11,6 +11,6 @@
   "engines": {
     "firefox": ">=38.0a1",
     "fennec": ">=38.0a1",
-    "seamonkey": ">=2.0a1"
+    "seamonkey": ">=2.0a1 <=2.46"
   }
 }