Mark optional params as Optional (pydantic#5128)

* Mark optional params as Optional

* Fix invalid optionals

Caught by @hramezani

---------

Co-authored-by: JensHeinrich <github.com/JensHeinrich>

pydantic/fields.py

@@ -223,28 +223,28 @@ def Field(
     default: Any = Undefined,
     *,
     default_factory: Optional[NoArgAnyCallable] = None,
-    alias: str = None,
-    title: str = None,
-    description: str = None,
-    exclude: Union['AbstractSetIntStr', 'MappingIntStrAny', Any] = None,
-    include: Union['AbstractSetIntStr', 'MappingIntStrAny', Any] = None,
-    const: bool = None,
-    gt: float = None,
-    ge: float = None,
-    lt: float = None,
-    le: float = None,
-    multiple_of: float = None,
-    allow_inf_nan: bool = None,
-    max_digits: int = None,
-    decimal_places: int = None,
-    min_items: int = None,
-    max_items: int = None,
-    unique_items: bool = None,
-    min_length: int = None,
-    max_length: int = None,
+    alias: Optional[str] = None,
+    title: Optional[str] = None,
+    description: Optional[str] = None,
+    exclude: Optional[Union['AbstractSetIntStr', 'MappingIntStrAny', Any]] = None,
+    include: Optional[Union['AbstractSetIntStr', 'MappingIntStrAny', Any]] = None,
+    const: Optional[bool] = None,
+    gt: Optional[float] = None,
+    ge: Optional[float] = None,
+    lt: Optional[float] = None,
+    le: Optional[float] = None,
+    multiple_of: Optional[float] = None,
+    allow_inf_nan: Optional[bool] = None,
+    max_digits: Optional[int] = None,
+    decimal_places: Optional[int] = None,
+    min_items: Optional[int] = None,
+    max_items: Optional[int] = None,
+    unique_items: Optional[bool] = None,
+    min_length: Optional[int] = None,
+    max_length: Optional[int] = None,
     allow_mutation: bool = True,
-    regex: str = None,
-    discriminator: str = None,
+    regex: Optional[str] = None,
+    discriminator: Optional[str] = None,
     repr: bool = True,
     **extra: Any,
 ) -> Any:
@@ -402,7 +402,7 @@ def __init__(
         default_factory: Optional[NoArgAnyCallable] = None,
         required: 'BoolUndefined' = Undefined,
         final: bool = False,
-        alias: str = None,
+        alias: Optional[str] = None,
         field_info: Optional[FieldInfo] = None,
     ) -> None: