Remove unused PYDANTIC_AI_HOME import from tests

Author: uriyyo

tests/test_cli.py

@@ -23,7 +23,7 @@
     from prompt_toolkit.output import DummyOutput
     from prompt_toolkit.shortcuts import PromptSession
 
-    from pydantic_ai._cli import LAST_CONVERSATION_FILENAME, PYDANTIC_AI_HOME, cli, cli_agent, handle_slash_command
+    from pydantic_ai._cli import LAST_CONVERSATION_FILENAME, cli, cli_agent, handle_slash_command
     from pydantic_ai.models.openai import OpenAIChatModel
 
 pytestmark = pytest.mark.skipif(not imports_successful(), reason='install cli extras to run cli tests')