chore: remove test_changes.py from root directory

This test file was used for local development and verification
but should not be part of the PR. It was causing import conflicts
in CI environments.

All necessary test coverage is already provided by tests/ directory:
- tests/test_entities.py includes updated tests for Issue #25

Signed-off-by: Dmitrii Efremov <kaidendev@icloud.com>

Author: KvizadSaderah