types: added global URL type to `MockMatcherUrl`

[flevi29]

In the docs the second entry to Argument values states that url can be any of String and URL, however the types do not support URL.

[flevi29]

It seems that karma-webpack 3.0.5 needs webpack@"^2.0.0 || ^3.0.0", but the current version sits at 4.46.0. NPM is strict with peers. There are 3 options:

1. Use --legacy-peer-deps when installing dependencies (dirty, peer deps are enforced for a good reason in my opinion)
2. Update karma
3. Downgrade webpack

[flevi29]

I am not sure what to do about the last issue, tests seem to pass alright. It's a coveralls issue, token related or something similar. Can you do something about it @wheresrhys ?

[wheresrhys]

Thanks for this. I will pull this change into fetch-mock@10