fix(preset): class-properties and private-methods need to have same loose value

[stonebk]

Started getting the following warning recently:

Though the "loose" option was set to "false" in your @babel/preset-env config, it will not be used for @babel/plugin-proposal-private-methods since the "loose" mode option was set to "true" for @babel/plugin-proposal-class-properties.
The "loose" option must be the same for @babel/plugin-proposal-class-properties, @babel/plugin-proposal-private-methods and @babel/plugin-proposal-private-property-in-object (when they are enabled): you can silence this warning by explicitly adding
        ["@babel/plugin-proposal-private-methods", { "loose": true }]
to the "plugins" section of your Babel config.

Found a discussion in another projects that seemed similar:
nuxt/nuxt#9224

I actually tried this fix already, unfortunately it doesn't seem to resolve the warning. My current workaround is to include the class-properties and private-methods plugins myself in the babel.config.js where the babel-plugin-zillow preset is being used.

[ahutchings]

Closing in favor of #12