RFE: Generate PEP 503 compatible (Build)Requires on Fedora (no dots in python3dist)

Since Fedora 33, we generate both `python3dist(foo.bar)` and `python3dist(foo-bar)` provides, but we'd like to follow [PEP 503](https://www.python.org/dev/peps/pep-0503/#normalized-names) and use only the names with dashes.

However, packagers keep adding manual BuildRequires with dots because pyp2rpm generates them. I've just opened 25 pull requests for Fedora to remove that pattern and it would be really great if pyp2rpm could generate the names according to PEP 503 too.

Slightly problematic thing is that EPEL 8 does not support that, so for EPEL 8 spec files, the dot needs to be there.

An alternative that is compatible both with past EPELs and future Fedoras is to use the `%py3_dist` macro.

Thanks