Enable working under Python 3.8

[jnwatson]

No description provided.

[codecov]

Codecov Report

Merging #1907 into master will increase coverage by 0.09%.
The diff coverage is 94.73%.

@@            Coverage Diff             @@
##           master    #1907      +/-   ##
==========================================
+ Coverage   96.59%   96.69%   +0.09%     
==========================================
  Files         139      139              
  Lines       26225    26412     +187     
==========================================
+ Hits        25331    25538     +207     
+ Misses        894      874      -20     

Flag	Coverage Δ
#linux	96.69% <94.73%> (+0.09%)	⬆️
#linux_replay	71.09% <63.15%> (+0.03%)	⬆️

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Impacted Files	Coverage Δ
synapse/lib/httpapi.py	94.75% <ø> (-0.02%)	⬇️
synapse/lib/lmdbslab.py	99.59% <ø> (+0.10%)	⬆️
synapse/lib/nexus.py	96.81% <ø> (ø)
synapse/lib/snap.py	94.58% <ø> (-0.17%)	⬇️
synapse/lib/stormsvc.py	97.22% <ø> (ø)
synapse/lib/types.py	97.84% <ø> (+<0.01%)	⬆️
synapse/lib/view.py	96.03% <ø> (+1.47%)	⬆️
synapse/cortex.py	95.99% <75.00%> (+0.19%)	⬆️
synapse/daemon.py	89.57% <100.00%> (ø)
synapse/lib/base.py	95.20% <100.00%> (+2.92%)	⬆️
... and 37 more

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