[BUG] Fix support for newer mkdocstring versions

[abhiTronix]

Brief Description

Currently, mkdocstring >0.17.0 fails to generate Automatic documentation due to some recent changes in its API.

Acknowledgment

• [x] I have searched the issues for my issue and found nothing related or helpful.
• [x] I have read the DeFFcode Documentation.
• [x] I have read the DeFFcode Issue Guidelines.

Current Environment

• My DeFFcode version: 0.2.2
• My Python version: 3.7+
• My Pip version: latest
• My Operating System and its version: all

Expected Behavior

mkdocstring >0.17.0 must able to generate Automatic documentation.

Actual Behavior

mkdocstring >0.17.0 fails to generate Automatic documentation.

Possible Fix

Move to mkdocstrings-python-legacy handler.

Miscellaneous

None