Add null to abi and screenshots properties of ApklisReleaseModel

[leynier]

No description provided.

[codecov]

Codecov Report

Merging #12 (4aa4a59) into main (7a12673) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##              main       #12   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           14        14           
  Lines           74        74           
=========================================
  Hits            74        74           

Impacted Files	Coverage Δ
...pklis_web_api/lib/models/apklis_release_model.dart	100.00% <ø> (ø)

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