Use theme colour for upload progress bar

[realies]

Currently, despite the custom theme colour, the upload progress bar in the web UI stays blue.

[juliusknorr]

@realies Thanks for reporting. Unfortunately I'm unable to reproduce this on current master. Please fill out the issue template to provide some more details on your setup.

[juliusknorr]

Closing this since I could not reproduce that and missing issue template. Feel free to reopen with more details provided.

[realies]

@juliushaertl, unfortunately this is still the case with 12.0.5. It is reproducible when you set the theming color to #000000.

[juliusknorr]

@realies Thanks, yes I can reproduce that in 12.0.5