[V3] Update code standards (black code format pass) (#1650)

* ran black: code formatter against `redbot/` with `-l 99`

* badge

redbot/core/utils/data_converter.py

@@ -28,7 +28,7 @@ class DataConverter:
             The file isn't valid JSON
         """
         try:
-            with file_path.open(mode='r', encoding='utf-8') as f:
+            with file_path.open(mode="r", encoding="utf-8") as f:
                 data = json.load(f)
         except (FileNotFoundError, json.JSONDecodeError):
             raise