Apply nullability attributes to TimeChangedEventArgs type as well

[egvijayanand]

Description

Nullability changes for DatePicker and TimePicker.

It seems nullability not applied to TimeChangedEventArgs type.

maui/src/Controls/src/Core/TimeChangedEventArgs.cs

Lines 20 to 28 in 84331b3

	/// <summary>The time that the user entered.</summary>
	/// <value>To be added.</value>
	/// <remarks>To be added.</remarks>
	public TimeSpan NewTime { get; private set; }
	/// <summary>The time that was on the element at the time that the user selected it.</summary>
	/// <value>To be added.</value>
	/// <remarks>To be added.</remarks>
	public TimeSpan OldTime { get; private set; }

Public API Changes

Type of both the NewTime and OldTime properties is to be updated as TimeSpan?

Intended Use-Case

Nullability changes

[jsuarezruiz]

Already merged PR.