add click.types.DateTime to click stubs (#2958)

third_party/2and3/click/types.pyi

@@ -1,4 +1,5 @@
 from typing import Any, Callable, IO, Iterable, List, Optional, TypeVar, Union, Tuple as _PyTuple, Type
+import datetime
 import uuid
 
 from click.core import Context, Parameter, _ParamType as ParamType, _ConvertibleType
@@ -35,6 +36,22 @@ class Choice(ParamType):
         ...
 
 
+class DateTime(ParamType):
+    def __init__(
+        self,
+        formats: Optional[List[str]] = ...,
+    ) -> None:
+        ...
+
+    def convert(
+        self,
+        value: str,
+        param: Optional[Parameter],
+        ctx: Optional[Context],
+    ) -> datetime.datetime:
+        ...
+
+
 class FloatParamType(ParamType):
     def __call__(
         self,