Upgrade black to 21.4b0 and reformat (#5250)

This introduces newlines before decorators.

stubs/Werkzeug/werkzeug/utils.pyi

@@ -36,6 +36,7 @@ def unescape(s): ...
 # 'redirect' returns a werkzeug Response, unless you give it
 # another Response type to use instead.
 _RC = TypeVar("_RC", bound=Response)
+
 @overload
 def redirect(location: str, code: int = ..., Response: None = ...) -> Response: ...
 @overload

stubs/click/click/termui.pyi

@@ -26,6 +26,7 @@ def echo_via_pager(
 ) -> None: ...
 
 _T = TypeVar("_T")
+
 @overload
 def progressbar(
     iterable: Iterable[_T],

stubs/dataclasses/dataclasses.pyi

@@ -9,6 +9,7 @@ _T = TypeVar("_T")
 class _MISSING_TYPE: ...
 
 MISSING: _MISSING_TYPE
+
 @overload
 def asdict(obj: Any) -> Dict[str, Any]: ...
 @overload

stubs/first/first.pyi

@@ -2,6 +2,7 @@ from typing import Any, Callable, Iterable, Optional, TypeVar, Union, overload
 
 _T = TypeVar("_T")
 _S = TypeVar("_S")
+
 @overload
 def first(iterable: Iterable[_T]) -> Optional[_T]: ...
 @overload

stubs/redis/redis/utils.pyi

@@ -6,6 +6,7 @@ from .client import Pipeline, Redis
 _T = TypeVar("_T")
 
 HIREDIS_AVAILABLE: bool
+
 @overload
 def from_url(url: Text, db: Optional[int] = ..., *, decode_responses: Literal[True], **kwargs: Any) -> Redis[str]: ...
 @overload