Apply suggestion from @benjamincanac - correctly type based on theme

Co-authored-by: Benjamin Canac <[email protected]>

Author: mikenewbon

src/runtime/components/Calendar.vue

@@ -91,7 +91,7 @@ export interface CalendarProps<R extends boolean = false, M extends boolean = fa
   /**
    * @defaultValue 'solid'
    */
-  variant?: 'solid' | 'outline' | 'soft' | 'subtle' | 'ghost'
+  variant?: Calendar['variants']['variant']
   defaultValue?: CalendarDefaultValue<R, M>
   modelValue?: CalendarModelValue<R, M>
   class?: any