Fix issue 68

[elad-c]

Pull Request Description:

Add support and tests for negative channel_axis in Keras weight quantizers Closes #68

Checklist before requesting a review:

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