test: Update test environment and VCR configuration

- Add mock_openai_key fixture for consistent test API key
- Update VCR configuration to record API interactions
- Update test cases to handle None and whitespace inputs

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

tests/conftest.py

@@ -8,6 +8,11 @@ from dotenv import load_dotenv
 
 load_result = load_dotenv(override=True)
 
+@pytest.fixture(autouse=True)
+def mock_openai_key(monkeypatch):
+    """Mock OpenAI API key for VCR cassettes."""
+    monkeypatch.setenv("OPENAI_API_KEY", "sk-fake-test-key-12345")
+
 @pytest.fixture(autouse=True)
 def setup_test_environment():
     """Set up test environment with a temporary directory for SQLite storage."""