Incompatible with webpack

[pastelsky]

When trying to build useragent with webpack, the build errors out because packages request and yamlparser are used by this library (lib/update.js), but they aren't specified as either peer dependencies or dependencies.

This means the package cannot be used on the client side at the moment.

[vith]

This PR looks related #117

[nicollecastrog]

I'm using next.js (which uses webpack) and found a work-around. I've commented here: #117 (comment)

[jdrydn]

Only solution I found was to install yamlparser alongside until this is fixed, ah well 🤷‍♂️