Add more aiohttp typing

[jettify]

No description provided.

[codecov]

Codecov Report

Merging #117 into master will increase coverage by 0.02%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #117      +/-   ##
==========================================
+ Coverage   97.75%   97.77%   +0.02%     
==========================================
  Files          12       12              
  Lines         490      495       +5     
  Branches       34       34              
==========================================
+ Hits          479      484       +5     
  Misses          5        5              
  Partials        6        6

Impacted Files	Coverage Δ
aiozipkin/span.py	98.31% <ø> (ø)	⬆️
aiozipkin/helpers.py	100% <ø> (ø)	⬆️
aiozipkin/aiohttp_helpers.py	96.61% <100%> (+0.14%)	⬆️

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