updated dependencies for ubuntu 24.04

[mschleie]

For working on Ubuntu 24.04 two dependencies must be changed, because they are missing in newer Ubuntu versions. These changes contain the update of the dependencies and their reference in the code. With these changes ocrd-browser can be build and run on Ubuntu 24.04.

[bertsky]

@hnesk a few comments how to proceed with this:

Currently, the Dockerfile base stage is python:3.8, which itself is based on Debian 12 Bookworm (similar to Ubuntu 22). So for consistency, this PR should change this to python:3.11, which is based on Debian 13 Trixie (similar to Ubuntu 24).

Oh, and the README needs to be updated, too.

However, following OCR-D convention, deps-ubuntu targets ocrd/core, which is currently based on ubuntu:22.04 (and has switched from 20.04 just recently). So I would recommend keeping this open until such time when OCR-D switches to ubuntu:24.04.