Add Python term entries for Multilevel, Multiple, and Hierarchical Inheritance

[Prankisster]

Description

Added three new term entries under Python inheritance:

• multilevel-inheritance.md
• multiple-inheritance.md
• hierarchical-inheritance.md

Each entry includes:

• Definition and use case
• Syntax explanation
• Example with explanation
• Codebyte example
• Diagram
• Related concepts

Issue Solved

Closes #7079
Closes #7080
Closes #7081

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.

[CLAassistant]

All committers have signed the CLA.

[CLAassistant]

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[mamtawardhani]

Hey @Prankisster, I'll request that you raise three different PRs for these three files on three other branches.

I'll close the PR for now, and assign the three issues to you, please raise the three PRs and let me know when you do. Thank you! 😄