✏️ Fix Pydantic examples in tutorial for Python types (#9961)

Co-authored-by: Sebastián Ramírez <tiangolo@gmail.com>

docs_src/python_types/tutorial011.py

@@ -6,7 +6,7 @@ from pydantic import BaseModel
 
 class User(BaseModel):
     id: int
-    name = "John Doe"
+    name: str = "John Doe"
     signup_ts: Union[datetime, None] = None
     friends: List[int] = []
 

docs_src/python_types/tutorial011_py310.py

@@ -5,7 +5,7 @@ from pydantic import BaseModel
 
 class User(BaseModel):
     id: int
-    name = "John Doe"
+    name: str = "John Doe"
     signup_ts: datetime | None = None
     friends: list[int] = []
 

docs_src/python_types/tutorial011_py39.py

@@ -6,7 +6,7 @@ from pydantic import BaseModel
 
 class User(BaseModel):
     id: int
-    name = "John Doe"
+    name: str = "John Doe"
     signup_ts: Union[datetime, None] = None
     friends: list[int] = []