Selecting a single week within `week-range` picker leads to multiple weeks being displayed in collapsed view

[nuernbergk]

Describe the bug
With a week-range picker, selecting just a single week and then hitting select leads to the collapsed DatePicker to display the current week as the end date of that range.

To Reproduce
Steps to reproduce the behavior:

1. Create a VueDatePicker element:

<VueDatePicker
    range
    week-picker
    v-model="dateRange"
    :week-start-day="1"
    :week-numbers="{ type: 'iso' }"
    :enable-time-picker="false"
    format="ww-yyyy"
/>

2. Select a single week:

4. Click select.
5. In the collapsed DatePicker, the a range of the selected week and the current week is displayed as selected

Although the v-model does not seem to be updated to reflect this.
7. When reopening the date viewer, the range seen in the preview is displayed as selected.

Note that this also happens when using the notoday property.

Expected behavior
I would expect the behaviour to be that of other partial ranges, i.e. when a single part of the range is selected, the collapsed view only shows that part of the range.

Desktop & mobile:

• Browser: Firefox, Chrome, Safari
• Library version: 9.0.1