Add prop-types to peer dependencies

there is a direct import from prop-types in ReactCodeInput.js

Author: acusti

package-lock.json

@@ -112,6 +112,7 @@
     "webpack-cli": "^2.1.3"
   },
   "peerDependencies": {
+    "prop-types": "^15",
     "react": "^15.5.4 ||^16.2.0 || ^17.0.0",
     "react-dom": "^15.5.4 ||^16.2.0 || ^17.0.0"
   }