Update intersphinx URLs.

[wRAR]

intersphinx inventory has moved: https://tox.readthedocs.io/en/latest/objects.inv -> https://tox.wiki/en/latest/objects.inv
intersphinx inventory has moved: https://scrapy.readthedocs.io/en/latest/objects.inv -> https://docs.scrapy.org/en/latest/objects.inv

[codecov]

Codecov Report

Merging #224 (f062b2c) into master (181a70f) will not change coverage.
The diff coverage is n/a.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #224   +/-   ##
=======================================
  Coverage   96.18%   96.18%           
=======================================
  Files           9        9           
  Lines         498      498           
  Branches       94       94           
=======================================
  Hits          479      479           
  Misses          9        9           
  Partials       10       10