follow up `pkgmt version`

[edublancas]

once we finish #60

• when the version_file is an empty file, the error is unclear:

AttributeError: 'NoneType' object has no attribute 'group'

• error message does not accurately display the location of the customized version file:

- [Inconsistent version] Version in  top section in CHANGELOG is '0.1.42dev', but version in __init__.py is '0.1.40dev', fix them so they match

[edublancas]

since we closed #60, let's work on this one

[neelasha23]

Acceptance criteria:

1. If version file is empty or __version__ string not present, raise click.ClickException : Please add version string in <version_file_path> , e.g., __version__ = '0.1dev'.
2. Add version file path in error message when versions in version file and changelog do not match.
3. Test cases for both projects with version file in pyproject.toml and otherwise.
4. Changelog entry.

[neelasha23]

@edublancas Is the AC looking ok?

[edublancas]

If version file is empty or version string not present, raise click.ClickException : Please add version string in , e.g., version = '0.1dev'.

here we can do something more generic, there's a function that parses the version value. if such function fails, we can raise an error and tell the user how the format should be

the rest looks good

[neelasha23]

Yes I have added generic parsing for raising the error in the PR