Replace deprecated Palette by PaletteLight

[hocinehacherouf]

Description

What's new?

• Palette is obsolete and will be abstract in a future update of Mudblazor. It must be replaced by PaletteLight or PaletteDark or custom implementation. In our case, we need to replace it by PaletteLight.

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• Tests
• Other

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (90f3afd) 92.39% compared to head (eb05e25) 92.39%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2112   +/-   ##
=======================================
  Coverage   92.39%   92.39%           
=======================================
  Files         277      277           
  Lines        9129     9129           
=======================================
  Hits         8435     8435           
  Misses        694      694           

Impacted Files	Coverage Δ
src/AzureIoTHub.Portal.Client/Constants/Theme.cs	100.00% <100.00%> (ø)

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