🤖 chore: Add cover key in .babel.env.

These changes were automatically generated by a transform whose code can be found at:
  - https://github.com/aureooms/rejuvenate/blob/0b1f4a716129255387221dbf9e12a57770484b04/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

@@ -156,6 +156,7 @@
           ]
         ]
       },
+      "cover": {},
       "development": {
         "presets": [
           "babel-preset-power-assert"