FIX: Blacklist coverage >=5

[effigies]

While we're waiting on nedbat/coveragepy#915, let's get CI back up and running...

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@7d8d7cb). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #209   +/-   ##
=========================================
  Coverage          ?   77.37%           
=========================================
  Files             ?       18           
  Lines             ?     1043           
  Branches          ?      187           
=========================================
  Hits              ?      807           
  Misses            ?      148           
  Partials          ?       88

Flag	Coverage Δ
#ds003	77.37% <ø> (?)

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