refactor(theme): remove global theme attribute from doc

Author: dysfunc

docs/src/App.svelte

@@ -26,9 +26,7 @@
     The <code>DatePicker</code> component allows users to easily select a date or date-range from one or more calendars.
 
     <div class="showcase">
-      <form on:submit={() => console.log('okoko')}>
-        <DatePicker startDate={getDateFromToday(29)} endDate={today} showYearControls={false} isMultipane showPresets isRange isOpen alwaysShow />
-      </form>
+      <DatePicker startDate={getDateFromToday(29)} endDate={today} showYearControls={false} isMultipane showPresets isRange isOpen alwaysShow />
     </div>
   </section>
 

src/datepicker.svelte

@@ -871,7 +871,6 @@
   $: endDateYear = endDateMonth === 0 ? startDateYear + 1 : startDateYear;
   $: endDateCalendar = calendarize(new Date(endDateYear, endDateMonth), startOfWeek);
   $: !isRange && (endDate = null);
-  $: theme !== null && globalThis.document?.documentElement.setAttribute('data-picker-theme', theme);
   $: disabled = getDatesFromArray(disabledDates);
   $: enabled = getDatesFromArray(enabledDates, true);