test: fix time-dependent tests in Date Range - Handle null start date

Add openToDate prop to ensure the calendar opens to November 2025
regardless of the current date. Without this, when startDate is null
and selectsRange is true, the calendar defaults to today's date.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: martijnrusschen

src/test/datepicker_test.test.tsx

@@ -4969,6 +4969,7 @@ describe("DatePicker", () => {
           startDate={null}
           selected={newDate(endDateLabel)}
           endDate={newDate(endDateLabel)}
+          openToDate={newDate(endDateLabel)}
           dateFormat="yyyy-MM-dd"
           onChange={onChangeSpy}
           isClearable
@@ -5003,6 +5004,7 @@ describe("DatePicker", () => {
           startDate={null}
           selected={newDate(endDateLabel)}
           endDate={newDate(endDateLabel)}
+          openToDate={newDate(endDateLabel)}
           dateFormat="yyyy-MM-dd"
           onChange={onChangeSpy}
           isClearable