all: Format with black.

Also activate auto formatting. Bump flake8 and mark black
disagreements in setup.cfg.

src/pybricks/ev3dev/_speaker.py

@@ -97,7 +97,7 @@ class Speaker:
         """
         pass
 
-    def set_volume(self, volume, which='_all_'):
+    def set_volume(self, volume, which="_all_"):
         """Sets the speaker volume.
 
         Arguments:

src/pybricks/ev3dev/_speaker.pyi

@@ -5,17 +5,16 @@ from typing import Iterable, Optional, Union
 
 from pybricks.media.ev3dev import SoundFile
 
-
 class Speaker:
     def beep(self, frequency: int = 500, duration: int = 100) -> None: ...
     def play_notes(self, notes: Iterable[str], tempo: int = 120) -> None: ...
     def play_file(self, file_name: Union[SoundFile, str]) -> None: ...
     def say(self, text: str) -> None: ...
     def set_speech_options(
-            self,
-            language: Optional[str] = None,
-            voice: Optional[str] = None,
-            speed: Optional[int] = None,
-            pitch: Optional[int] = None,
+        self,
+        language: Optional[str] = None,
+        voice: Optional[str] = None,
+        speed: Optional[int] = None,
+        pitch: Optional[int] = None,
     ): ...
     def set_volume(self, volume: int, which: str = "_all_") -> None: ...