Remove deprecated URL API usage

[JamieMagee]

The legacy URL API (provided by require('url')) was deprecated by NodeJS 11 released in October 2018. It is scheduled to be removed in a future release.

The main motivation for this change, is Yarn v2, which does not allow undeclared dependencies to be used. require('url') is ambiguous between the built-in NodeJS module, and the npm package url. I'm assuming the intent is to use the built-in module, so I've migrated to using the new URL API, for which the import is implicit.

[bryanmacfarlane]

Thanks for pointing that out! Can you create an issue highlighting the issues and details? I want to make sure that if someone is pinning to an older http client and at some point in the future it fails, there's a good searchable issue that folks can add comments to later.

[JamieMagee]

@bryanmacfarlane Sure! Opened #26

[bryanmacfarlane]

Thanks @JamieMagee for this contribution!

[kouberl]

Hello,
I'm not sure but I think
the line

proxyAuth:` ${proxyUrl.username}:${proxyUrl.password}`,

breaks some libraries which are using this library when setting a proxy url without username and password. proxyAuth will be set to ":"

I have a issue at docker/setup-buildx-action: docker/setup-buildx-action#57