docs: Add new term entry for Multilevel Inheritance in Python

[Prankisster]

Description

This PR adds a new term entry under the Inheritance section in Python: Multilevel Inheritance. The new file is created at:
content/python/concepts/inheritance/terms/multilevel-inheritance/multilevel-inheritance.md

Issue Solved

Closes #7080

Type of Change

• Adding a new entry

Checklist

• All writings are my own.
• My entry follows the Codecademy Docs style guide.
• My changes generate no new warnings.
• I have performed a self-review of my own writing and code.
• I have checked my entry and corrected any misspellings.
• I have made corresponding changes to the documentation if needed.
• I have confirmed my changes are not being pushed from my forked main branch.
• I have confirmed that I'm pushing from a new branch named after the changes I'm making.
• I have linked any issues that are relevant to this PR in the Issues Solved section.

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