Fix M2M Logging for Event Types (Fixes Issue #324)

[nedagilanian]

✅ Summary

This PR addresses Issue #324, which involves the lack of logging for Many-to-Many (M2M) field changes in the django-easy-audit package. Specifically, it ensures that events related to M2M add, remove, and clear actions are properly logged, enabling full auditing capabilities for M2M fields.

🔧 What was done?

• Test Coverage:

  • Added tests to verify that M2M relations trigger the correct audit logs when fields are added, removed, or cleared.
  • The test cases now cover all M2M change scenarios for accurate auditing.

• Details of Changes:

  • M2M_ADD: Logs when tags are added to an article (Many-to-Many Add).
  • M2M_REMOVE: Logs when tags are removed from an article (Many-to-Many Remove).
  • M2M_CLEAR: Logs when all tags are cleared from an article (Many-to-Many Clear).

🔍 Why is this needed?
Previously, changes to Many-to-Many fields were not being captured correctly by the audit logging system, leading to incomplete event tracking. This PR ensures full auditing coverage for M2M field changes.

🛠️ Testing:

• Added comprehensive tests for M2M add, remove, and clear events.
• Verified that these events are properly logged with the correct event type (e.g., M2M_ADD, M2M_REMOVE, M2M_CLEAR).

🔗 Related Issue
Fixes #324

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Tested with Django 5.2 and Python 3.12.