Close existing 'Defer due date' window when opening another

[StrangePeanut]

Description

Opening another 'Defer due date' window causes the initial window to overlap the new one.

Vikunja Frontend Version

0.21.0+315-963d91c4d5

Vikunja API Version

v0.21.0+189-66afe52afb

Browser and version

Version 1.59.124 Chromium: 118.0.5993.117 (Official Build) (64-bit)

Can you reproduce the bug on the Vikunja demo site?

Yes

Screenshots