Fix lint and import issues in test file

- Remove unused imports (pytest, Crew) to fix lint errors
- Fix LiteAgent import path from crewai.lite_agent
- Resolves CI test collection error for Python 3.10

Co-Authored-By: João <joao@crewai.com>

tests/test_prompt_customization_docs.py

@@ -1,9 +1,9 @@
-import pytest
 from unittest.mock import Mock, patch
 from pydantic import BaseModel
 from typing import List
 
-from crewai import Agent, Task, Crew, LiteAgent
+from crewai import Agent, Task
+from crewai.lite_agent import LiteAgent
 from crewai.utilities.prompts import Prompts
 from crewai.utilities import I18N