Rename 'PersonApp.py' to 'person_app.py'

[Prikshit7766]

Description

This PR renames 'PersonApp.py' to 'person_app.py' to follow snake case convention and updates related imports accordingly.

Fixes #667

• Refactor (does not change functionality, e.g. code style improvements, linting)

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• I have checked my code and corrected any misspellings

Maintainer Checklist

• closes Rename apps/PersonApp.py to follow snake case convention #667
• Made sure Checks passed

[codecov]

Codecov Report

All modified lines are covered by tests ✅

Files	Coverage Δ
embedchain/__init__.py	100.00% <100.00%> (ø)
embedchain/apps/person_app.py	51.35% <ø> (ø)

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[Prikshit7766]

@deshraj
Thanks for approving the PR. If everything's okay, can you please merge it?