feat: allow stubs package

[trim21]

close #332

• do not try to get docstring and version if it's not dynamic, which is typical the case of stubs package
• do not raise exception if it's -stubs package without __init__.py
• do not normalize the -stubs parts in package name

[cdce8p]

Thanks for working on this @trim21! It will be a great addition to have. Left a few comments below.

[cdce8p]

Some last comments

[cdce8p]

Thanks a lot @trim21! This looks good to me. Will wait a few more days before merging to give others the chance to comment.