Set the default value for Interval to match DefaultValue (should fix e…

…lsa-workflows#4818) (elsa-workflows#4926)

src/modules/Elsa.Scheduling/Activities/Timer.cs

@@ -34,7 +34,7 @@ public Timer(Input<TimeSpan> interval, [CallerFilePath] string? source = default
  /// The interval at which the timer should execute.
  /// </summary>
  [Input(Description = "The interval at which the timer should execute.", DefaultValue = "00:01:00")]
- public Input<TimeSpan> Interval { get; set; } = default!;
+ public Input<TimeSpan> Interval { get; set; } = new(TimeSpan.FromMinutes(1));
 
  /// <inheritdoc />
  protected override async ValueTask ExecuteAsync(ActivityExecutionContext context)