remove python 2 style codes from across the codebase

[auvipy]

No description provided.

[codecov]

Codecov Report

Merging #500 (17efcbe) into master (74fb5c1) will not change coverage.
The diff coverage is 95.00%.

@@           Coverage Diff           @@
##           master     #500   +/-   ##
=======================================
  Coverage   84.61%   84.61%           
=======================================
  Files          50       50           
  Lines        2061     2061           
=======================================
  Hits         1744     1744           
  Misses        317      317           

Impacted Files	Coverage Δ
silk/request_filters.py	65.40% <92.85%> (ø)
silk/collector.py	89.78% <100.00%> (ø)
silk/model_factory.py	83.84% <100.00%> (ø)
silk/storage.py	100.00% <100.00%> (ø)

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