update for WinUI .net6

[ChrisPulman]

What kind of change does this PR introduce?

update

What is the current behaviour?

supports .net5

What is the new behaviour?

supports .net6

What might this PR break?

Please check if the PR fulfils these requirements

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

Other information:

[codecov]

Codecov Report

Merging #2903 (4ebad35) into main (1de2e78) will increase coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #2903      +/-   ##
==========================================
+ Coverage   72.19%   72.21%   +0.02%     
==========================================
  Files         140      140              
  Lines        4906     4906              
==========================================
+ Hits         3542     3543       +1     
+ Misses       1364     1363       -1     

Impacted Files	Coverage Δ
src/ReactiveUI.Uwp/Common/RoutedViewHost.cs	88.13% <ø> (+1.69%)	⬆️

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[github-actions]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.