fix: move plugin to dev dependencies

Author: Lodin

package-lock.json

@@ -58,6 +58,7 @@
     "@babel/core": "^7.7.4",
     "@babel/plugin-proposal-class-properties": "^7.7.4",
     "@babel/plugin-proposal-object-rest-spread": "^7.7.4",
+    "@babel/plugin-proposal-optional-chaining": "^7.7.4",
     "@babel/plugin-transform-runtime": "^7.7.4",
     "@babel/preset-env": "^7.7.4",
     "@babel/preset-react": "^7.7.4",
@@ -110,7 +111,6 @@
     "react-window": "^1.8.5"
   },
   "dependencies": {
-    "@babel/plugin-proposal-optional-chaining": "^7.7.4",
     "@babel/runtime": "^7.7.4"
   }
 }