fix Command Scheduler not set to immediate where required for CanExecute

[ChrisPulman]

What kind of change does this PR introduce?

fix

What is the current behaviour?

Tests do not pass

What is the new behaviour?

Tests now pass

What might this PR break?

N/A

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 #2849 (c287849) into main (77e217d) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #2849   +/-   ##
=======================================
  Coverage   71.83%   71.83%           
=======================================
  Files         137      137           
  Lines        4828     4828           
=======================================
  Hits         3468     3468           
  Misses       1360     1360           

Impacted Files	Coverage Δ
.../ReactiveUI/ReactiveCommand/ReactiveCommandBase.cs	100.00% <ø> (ø)

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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.