Build against .NET 5 and .NET 6

[ronaldbarendse]

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 matches 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

I noticed ImageSharp already added .NET 5 and .NET 6 builds in SixLabors/ImageSharp#1745, but ImageSharp.Web is still only built against .NET Core 2.1 (support ended on August 21, 2021) and .NET Core 3.1 (support ends December 3, 2022, see MS support policy).

[ronaldbarendse]

FYI GitHub Actions soon won't be able to build .NET Core 2.1 projects anymore: actions/runner-images#4871. Because it's already out of support, I recommend dropping this framework version before v2 ships.

[JimBobSquarePants]

I won’t be dropping it while it’s still supported. V2 is designed as a baseline so I can drop targets with V3. (Same principle upstream with ImageSharp.

Regarding this PR. You’ll need to wire things up for testing against .NET 5/6 in the same manner as ImageSharp

[codecov]

Codecov Report

Merging #216 (616d943) into main (b86a247) will not change coverage.
The diff coverage is n/a.

@@         Coverage Diff         @@
##           main   #216   +/-   ##
===================================
  Coverage    85%    85%           
===================================
  Files        71     71           
  Lines      1945   1945           
  Branches    286    286           
===================================
  Hits       1672   1672           
  Misses      195    195           
  Partials     78     78           

Flag	Coverage Δ
unittests	85% <ø> (ø)

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

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b86a247...616d943. Read the comment docs.

[ronaldbarendse]

I've implemented a similar build pipeline as ImageSharp and everything seems to build fine (it just needs a different required check for code coverage: Build (windows-latest, net6.0, -x64, true)).

[Nuklon]

I won’t be dropping it while it’s still supported. V2 is designed as a baseline so I can drop targets with V3. (Same principle upstream with ImageSharp.

2.1 is already EOL and unsupported since August 21, 2021, and in 11 days it's also gone from GH Actions.

[ronaldbarendse]

2.1 is already EOL and unsupported since August 21, 2021, and in 11 days it's also gone from GH Actions.

Unsupported by Microsoft yes, but that doesn't stop people from still using it 😉 .NET Core 2.1 won't be included on the default images of GitHub Actions, but that isn't a problem as this build script already installs all required .NET SDKs...

And as @JimBobSquarePants mentioned, dropping support can be done in the next major version, so it aligns with the ImageSharp library.

[JimBobSquarePants]

This is great. Thanks!