fix: Remove duplicate Protocol import

- Remove Protocol import from typing to fix type checker error
- Keep Protocol from typing_extensions

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

src/crewai/flow/flow.py

@@ -13,7 +13,6 @@ from typing import (
     Generic,
     List,
     Optional,
-    Protocol,
     Set,
     Type,
     TypeVar,