🤖 chore(package.json): Configure prettier.

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/prettier:config.js
Please contact the author of the transform if you believe there was an error.

package.json

@@ -191,5 +191,8 @@
         ]
       }
     }
+  },
+  "prettier": {
+    "trailingComma": "all"
   }
 }