utils.py: fix types in docstrings for base64url_encode/decode

[romanek-adam]

No description provided.

[codecov]

Codecov Report

Merging #269 (f5d96d8) into master (be8e914) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #269   +/-   ##
=======================================
  Coverage   92.94%   92.94%           
=======================================
  Files          15       15           
  Lines        1418     1418           
=======================================
  Hits         1318     1318           
  Misses        100      100           

Impacted Files	Coverage Δ
jose/utils.py	100.00% <ø> (ø)

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[clesiemo3]

good fix for the same issue I'm having with PyCharm warning that I'm passing bytes as well as my initial confusion getting an exception when passing a string. I'm not sure why this PR hasn't been merged yet.