Support Base64QRCode on .NET6+ on Linux

[Shane32]

Summary

This PR allows Base64QRCode to be used with .NET 6+ on Linux as long as the requested image type is PNG.

Test plan

Tests have been added to the codebase

Closing issues

Fixes:

• Memory leak occurs when QR codes used Base64QRCode class #466
• Base64QRCode Type load fail using .net 6 #442
• Base64QRCode class seems to be missing from the latest build #451
• Base64QRCode does not exist in 1.4.3 #361

[Shane32]

@codebude Along with supporting SVG and PDF files on Linux, adding support for base64-encode PNG files is rather simple; PNG is the default encoder for Base64QRCode anyway. It also provides a notable performance optimization for base64-encoded PNG files regardless of platform.

[Shane32]

I've made suggestions based on your comments; please review again @codebude - thanks!

[codebude]

@Shane32 looks good.

Reminder to myself: update change log and compatibility matrix.

[codebude]

Updated compatibility table in the wiki. Diff: https://github.com/codebude/QRCoder/wiki/Advanced-usage---QR-Code-renderers/_compare/5ac75991cc326f1a70576b67eccf8012702fc557...588755ac6c039ee4075db9edfa6095238161749d

Updated release notes: https://github.com/codebude/QRCoder/wiki/Release-Notes/_compare/4f2a8764819813c17f1470c7661d21734de1b8aa...e52cf08e64a6789eff05690d24dcc7e8e6edbcc4

[aligneddev]

We just ran into this issue and I was thankful to see this PR is merged in.

I'm sure you have a lot of testing and things going on, so please forgive my eagerness, but do you have a timeline for the next release?

Thanks for all your work @codebude and @Shane32!

[codebude]

Hi @aligneddev

[...] but do you have a timeline for the next release?

Yesterday! Joking aside, there is only one open PR (#503) left, which I would like to review and merge, before I release the next version (1.5.0). So if nothing unforseen happens, you can expect the release within the next 2-3 days.