resolve false negatives due to hashes in requirements file

[redshiftzero]

Fixes #227

[codecov]

Codecov Report

Merging #248 into master will increase coverage by 0.14%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #248      +/-   ##
==========================================
+ Coverage   74.28%   74.43%   +0.14%     
==========================================
  Files           7        7              
  Lines         350      352       +2     
==========================================
+ Hits          260      262       +2     
  Misses         90       90

Impacted Files	Coverage Δ
safety/util.py	62.29% <100%> (+1.27%)	⬆️

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[rafaelpivato]

This looks great. Thanks for that!