Fix minted input file not found with recent TeX Live

This upgrades CI to use https://github.com/florian-h05/texlive-docker-builder, as smaller (1,15 GB) and more recent (TeX Live 2024) image for building the slides.

CI builds using TeX Live 2022 worked fine, but builds using TeX Live 2024 failed due to missing the input file. The file was existent on FS, but not properly recognized as input file by TeX Live and missing in the .fls file.

I have also modified the appearance of the darkcodesmall block.

Please note that the KIT dark theme seems to need some adjustments for the recent minted version, as it looks like the following now:

Using the vs theme, it looks much better:

Without any type of style adjustments, just using newer TeX Live and minted, it looks like this: