Add prompts for branch name, Python version, and test OS selection

[synacktraa]

PR Checklist

• A description of the changes is added to the description of this PR.
• If you've fixed a bug or added code that should be tested, add tests!
• If there is a related issue, make sure it is linked to this PR.
• Documentation in docs is updated

Description of changes

• Branch name prompt (My default repository branch is master, so a prompt would be really helpful).
• Minor python version prompt so the user can decide the version matrix to use. It applies to .github, tox.ini and pyproject.toml. Selected minor version is applied to Dockerfile.
• test_on_{os} prompts so the user can decide the os matrix to use. Defaults to ubuntu-latest. I would like to make these prompts dependent on include_github_actions but cookiecutter still hasn't merged the conditional prompt feature.
• Pytest coverage is not ran if codecov is disabled. Solves this issue: Pytest still tries to run coverage when codecov is not enabled #128

[fpgmaas]

@synacktraa Thanks for your suggestions! Some feedback;

• Providing the option for a minor python version; yes, let's add that. Maybe rename it to main python version instead?
• branch name prompt; I think main is the defacto standard today, so I don't think we should provide the option for a main branch name.
• test on multiple OS's. I think this could be useful. However, I'd prefer to see it in a separate PR so it's easier to review in depth. Is that possible?
• pytest coverage fix, obviously good to merge.