fix: add required dep on @babel/core

Author: kentcdodds

package.json

@@ -34,6 +34,7 @@
     "validate": "kcd-scripts validate"
   },
   "dependencies": {
+    "@babel/core": "^7.12.16",
     "@babel/preset-env": "^7.12.16",
     "@babel/preset-react": "^7.12.13",
     "@babel/preset-typescript": "^7.12.16",