Fix dependencies

Fix issue with absolute URLs containing non ASCII characters

A few workflow improvements

Fix issue with resolving relative URLs

Resolving `../..` against a base URL like `/foo/bar/` resulted in the
Resolver returning `//` as the path, which is wrong and leads to an
error. Fixed it.
Also updated the public suffixes and schemes lists and fixed a thing for
the latest version of PHP CS Fixer.

Support psr/http-message 2.0

Update list of schemes

Update schemes, suffixes and default ports

And year in LICENSE file.

Fix getting subdomain of URLs without subdomain

When a URL doesn't contain a subdomain part, the `subdomain()` method
returns `null`. This previously returned the whole domain (/host) which
was wrong/unwanted behaviour.

Remove docs and link to crwlr.software

As the docs for all versions of the package are also on crwlr.software
already for a while now, just link to there as it's also done in the
other packages.

Finalize changelog for v1.2.0