Add prop-types dependency

Author: Andrey Okonetchnikov

packages/react-design-tokens/package.json

@@ -12,13 +12,13 @@
     "clipboard-copy": "^3.0.0",
     "lodash": "^4.17.11",
     "polished": "^3.4.0",
-    "theme-ui": "^0.3.5"
+    "theme-ui": "^0.3.5",
+    "prop-types": "^15.7.2"
   },
   "devDependencies": {
     "primer-colors": "^1.0.1",
     "primer-spacing": "^1.0.2",
-    "primer-typography": "^1.0.1",
-    "prop-types": "^15.7.2"
+    "primer-typography": "^1.0.1"
   },
   "author": "Andrey Okonetchnikov <andrey@okonet.ru>",
   "license": "MIT",