Refs #25803 -- Documented npm compatibility in package.json

package.json

@@ -5,6 +5,9 @@
     "pretest": "eslint django/ js_tests/admin/ js_tests/gis/",
     "test": "grunt test --verbose"
   },
+  "engines": {
+    "npm": ">=1.3.0 <3.0.0"
+  },
   "devDependencies": {
     "eslint": "^0.22.1",
     "grunt": "^0.4.5",