Rename 'PersonApp.py' to 'person_app.py' (#752)

embedchain/__init__.py

@@ -6,6 +6,6 @@ from embedchain.apps.app import App  # noqa: F401
 from embedchain.apps.custom_app import CustomApp  # noqa: F401
 from embedchain.apps.Llama2App import Llama2App  # noqa: F401
 from embedchain.apps.open_source_app import OpenSourceApp  # noqa: F401
-from embedchain.apps.PersonApp import (PersonApp,  # noqa: F401
+from embedchain.apps.person_app import (PersonApp,  # noqa: F401
                                        PersonOpenSourceApp)
 from embedchain.vectordb.chroma import ChromaDB  # noqa: F401