chore: Fix test from #1142 (#1143)

Author: schloerke

tests/playwright/shiny/bugs/0648-update-slider-datetime-value/test_update_slider_datetime_value.py

@@ -37,8 +37,8 @@ def check_case(
 
     page.goto(local_app.url)
 
-    start_time = "2023-07-01 00:00:00"
-    end_time = "2023-07-01 01:00:00"
+    start_time = "2023-07-01 00:00:00+00:00"
+    end_time = "2023-07-01 01:00:00+00:00"
 
     check_case("one", value=(start_time, end_time))
     check_case(