20.0.1

Housekeeping:

• 8e33bf4 Housekeeping: Retire Xamarin due to end of support (#3797) @ChrisPulman
• a31490e Housekeeping Update Build to use dotnet build (#3799) @ChrisPulman
• 8b2f351 Housekeeping Tidy using's (#3798) @ChrisPulman
• 5ab874e Housekeeping: Prepare for Release (#3802) @ChrisPulman