LGTM is gone, remove/replace it

[marscher]

The service has been abondoned in favour of Github Code scanning. Details can be found here: https://github.blog/2022-08-15-the-next-step-for-lgtm-com-github-code-scanning/

We have some comments in the Python code skipping false positives. We should remove these comments. Additionally we have some badges in the readme which can be removed as well.

This has a low priority.

Then we should think about replacing the service with code scanning from Github.

[marscher]

This already has been migrated to CodeQL (Github code scanning, some time ago). Only the banners seem out of date then.

[marscher]

still, we have lgtm as status in PRs