chore(package): update prop-types to version 15.5.10

Closes #352

Author: greenkeeper[bot]

package.json

@@ -48,7 +48,7 @@
     "postcss-import": "9.1.0",
     "postcss-loader": "^2.0.5",
     "postcss-simple-vars": "^4.0.0",
-    "prop-types": "15.5.8",
+    "prop-types": "^15.5.10",
     "react": "15.5.4",
     "react-dom": "15.5.4",
     "react-draggable": "2.2.6",