fix: OnLocalTimeZoneChanged method (#5)

Refactor OnLocalTimeZoneChangedDetailed method to simplify time zone retrieval and improve clarity in null handling

(cherry picked from commit 41c54c6)

Author: arika0093

src/BlazorLocalTime/Components/LocalTimeForm.razor.cs

@@ -43,17 +43,16 @@ public void Dispose()
 
     private async void OnLocalTimeZoneChangedDetailed(object? sender, TimeZoneChangedEventArgs e)
     {
-        var prevTimeZone = e.PreviousTimeZone ?? LocalTimeService.BrowserTimeZoneInfo;
-        var currTimeZone = e.CurrentTimeZone ?? LocalTimeService.BrowserTimeZoneInfo;
+        var prevTimeZone = e.PreviousTimeZone;
+        var currTimeZone = e.CurrentTimeZone;
         if (currTimeZone == null)
         {
-            // If current timezone is null, we cannot proceed with the conversion.
-            // This can happen if the browser failed time zone detection.
+            // If current timezone is null, this can happen if the browser failed time zone detection.
             return;
         }
         if (prevTimeZone == null)
         {
-            // timezone is available now
+            // timezone is available now !
             await InvokeAsync(StateHasChanged);
             return;
         }