Update codcov and config

[JimBobSquarePants]

Prerequisites

• I have written a descriptive pull-request title
• I have verified that there are no overlapping pull-requests open
• I have verified that I am following the existing coding patterns and practice as demonstrated in the repository. These follow strict Stylecop rules 👮.
• I have provided test coverage for my change (where applicable)

Description

• Update coverlet.collector to 3.1.0
• Use integer precision for coverage calculation.
• Ignore patch coverage for checks.
• Use shared codecov.yml config from submodule

[codecov]

Codecov Report

Merging #1820 (3ac8b2b) into master (1997d59) will increase coverage by 0%.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master   #1820   +/-   ##
======================================
  Coverage      87%     87%           
======================================
  Files         936     936           
  Lines       48164   48164           
  Branches     6037    6037           
======================================
+ Hits        41998   42067   +69     
+ Misses       5162    5096   -66     
+ Partials     1004    1001    -3     

Flag	Coverage Δ
unittests	87% <ø> (+<1%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...rc/ImageSharp/Formats/Webp/Lossless/Vp8LEncoder.cs	97% <0%> (+<1%)	⬆️
...ageSharp/Formats/Webp/Lossless/PredictorEncoder.cs	98% <0%> (+5%)	⬆️
.../ImageSharp/Formats/Webp/Lossless/LosslessUtils.cs	97% <0%> (+6%)	⬆️

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[antonfirsov]

Thanks!

Isn't threshold something that can help us?

[JimBobSquarePants]

Isn't threshold something that can help us?

I don't really want to encourage allowing the percentage to drop. Let's give this a spin first.