Import Optional when property is nullable or not required

[dtkav]

Fixes #180

[codecov]

Codecov Report

Merging #177 into release/0.6.0 will not change coverage.
The diff coverage is 100.00%.

@@               Coverage Diff               @@
##           release/0.6.0      #177   +/-   ##
===============================================
  Coverage         100.00%   100.00%           
===============================================
  Files                 41        41           
  Lines               1271      1271           
===============================================
  Hits                1271      1271           

Impacted Files	Coverage Δ
openapi_python_client/parser/properties.py	100.00% <100.00%> (ø)

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[dtkav]

I'm not sure why, but codecov is reporting an error above.
When I click through to their website it seems to report 100% coverage.

[dbanty]

Thanks! I've cherry picked the fix to base it on main (#181) just so I can include it in a patch to 0.5 (since 0.6 will probably be a while still before final). This will go into both a 0.5.5 and a 0.6.0-alpha.2.

Regarding Codecov:
There is a single if statement that runs one way on 3.7 and a different on 3.8. CI runs on both and reports coverage on both. Codecov merges the coverages to get 100% but sometimes jumps the gun on setting build status here. Annoying but I haven't found a better way to do that yet.