Create pypi package & fix dependencies

[kruscpe1]

See also #1

What to do:

• Fix pyproject.toml to correctly build package
• Add package build to codeqc
• test-push & push to pypi as 0.1.1
• tag v0.1.1

[kruscpe1]

Test upload done here: https://test.pypi.org/project/torchsurv/

[kruscpe1]

@tcoroller will merge so main is up to date with the published version. I tried installing in an empty virtualenv and it worked for me. We could in principle also add a check for that to CICD.