🤖 chore: Add cover key in .babel.env.

These changes were automatically generated by a transform whose code can be found at:
  - https://github.com/make-github-pseudonymous-again/rejuvenate/blob/587dd807680b9b47d58146ef8f24224d84b87d34/src/transforms/package.json:ensure-babel-env-cover.js
Please contact the author of the transform if you believe there was an error.

package.json

@@ -117,6 +117,7 @@
           ]
         ]
       },
+      "cover": {},
       "development": {
         "sourceMaps": "inline",
         "presets": [