The __future__ statements we used were:
 - absolute_import - Mandatory in 3.0
 - with_statement - Mandatory in 2.6
 - print_function - Mandatory in 3.0

As we only support python >= 3.6 - this can be removed now

We were handling compat for py2 and py3 (mainly for urllib)
Now this is not required as we expect python >= 3.6

In py3 they are both str()
So, remove logic for the types as we support py3.6+ only

path2url was only used in 1 placce (in tests) so remove the function

And move url2path into the `__init__` file where it is used twice

This function was only used in 1 place and always with
encoding="utf-8" being hardcoded

So, remove the function and just use the logic required
because in py3.6+ it is a 1 liner: s.encode(...)

This function is a simple function now that we support only py3.6+
So, remove the original function and use the logic a required