PTB desktop icon isn't dark

[Kebap]

Brief summary of issue / Description of requested feature:

Mudlet PTB desktop icon should show in dark color (again?)

Steps to reproduce the issue / Reasons for adding feature:

1. Install PTB
2. Observe icon put on desktop
3. Icon looks like normal Mudlet

Error output / Expected result of feature

3. Icon should show night time

Extra information, such as the Mudlet version, operating system and ideas for how to solve / implement:

Noted with PTB 2024-02-19 on Win11