Support '/' character in HTTP password

[kristapsk]

It should be callers responsibility to properly encode URL.

This will unquote any %.., but is especially important for /, due to how urllib.parse.urlparse() works.

>>> import urllib.parse as urlparse
>>> url = urlparse.urlparse('http://user:pwdwith/slash@127.0.0.1:8332')
>>> print (url.username, url.password, url.hostname, url.port)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3.8/urllib/parse.py", line 177, in port
    raise ValueError(message) from None
ValueError: Port could not be cast to integer value as 'pwdwith'
>>> from requests.utils import quote
>>> url = urlparse.urlparse('http://user:{}@127.0.0.1:8332'.format(quote('pwdwith/slash', safe='')))
>>> print (url.username, url.password, url.hostname, url.port)
user pwdwith%2Fslash 127.0.0.1 8332
>>> print (url.username, urlparse.unquote(url.password), url.hostname, url.port)
user pwdwith/slash 127.0.0.1 8332

Will not work with Python2 as urlparse module does no thave unquote(). But Python2 is long time EOL and should not be used anyway.