Fix PyPI links

[reuvenperetz]

Pull Request Description:

Change URLs in README from relative to absolute. This way, regardless of where the markdown is rendered (GitHub, PyPI), the links will always point to the correct resource.

Checklist before requesting a review:

• I set the appropriate labels on the pull request.
• I have added/updated the release note draft (if necessary).
• I have updated the documentation to reflect my changes (if necessary).
• All function and files are well documented.
• All function and classes have type hints.
• There is a licenses in all file.
• The function and variable names are informative.
• I have checked for code duplications.
• I have added new unittest (if necessary).