🤖 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/eb1b209cd7aa675a642d48b2a788c2c6112779f7/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

@@ -153,7 +153,8 @@
           ]
         ],
         "sourceMaps": "inline"
-      }
+      },
+      "cover": {}
     }
   }
 }