Fix m2m saved when simple history disabled

[MattFanto]

Description

Fixing the following bug: m2m relationships ignores the SIMPLE_HISTORY_ENABLED = False, even when disabled the library is still saving the historical record.

Related Issue

Resolves #1328

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (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 change)

Checklist:

• I have run the pre-commit run command to format and lint.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have added my name and/or github handle to AUTHORS.rst
• I have added my change to CHANGES.rst
• All new and existing tests passed.

[ddabble]

Thank you, this should ensure that SIMPLE_HISTORY_ENABLED is properly taken into consideration in all cases 🙂

I added a test and improved the changelog slightly :)