update classnames to classNames

[circlecube]

This changes the expected method name from classname to className in order to make the method in use in the module consistent with the plugin.

• update a wppbh classname
• remove reference to classnames that is not needed

Proposed changes

Type of Change

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices apply)

Checklist

• I have read the CONTRIBUTING doc
• Linting and tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

Further comments