Update to league/uri 7.0

[acelaya]

The main incompatibility to update is that NotFoundRedirectResolver uses this to parse a URL that can originally contain placeholders.

v6 does not URL-encode the placeholders when present in the path, but v7 does, so the logic needs to be adjusted.

However, this logic was probably wrong in v6, as other psr-compatible URL parsers behave like v7 (that's probably why this library was introduced int the first place, as other libs are already a dependency and could have been used instead).

An alternative would be to stop using league/uri entirely if the logic can be refactored to work with any of the other dependencies.