🤖 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/a44c42967442d65fd14272682fb84a6f32feb841/src/transforms/package.json:ensure-babel-env-cover.js
Please contact the author of the transform if you believe there was an error.

Author: a-flying-potato

package.json

@@ -159,6 +159,7 @@
           ]
         ]
       },
+      "cover": {},
       "development": {
         "presets": [
           "babel-preset-power-assert"