Fix style to keep ruff and black happy.

src/hu/dotted_dict.py

@@ -27,7 +27,7 @@ def _apply_key(self, o, k):
         except ValueError:
             raise KeyError("Non-integer list subscript")
         except IndexError:
-            raise KeyError('Invalid list index at end of "{}"'.format(k[: self.pos]))
+            raise KeyError(f'Invalid list index at end of "{k[: self.pos]}"')
         except KeyError:
             raise KeyError(
                 'Unrecognised field name at end of "{}"'.format(k[: self.pos])
@@ -111,6 +111,6 @@ def _raise_error_if_syntax_error(self, key, match):
         if match is None:
             raise KeyError(
                 "Cannot find name or list subscript at start of {!r}".format(
-                    key[self.current_position:]
+                    key[self.current_position :]
                 )
             )

src/hu/object_dict.py

@@ -44,10 +44,11 @@ def __init__(self, arg=sentinel):
         if arg is self.sentinel:  # Called without args
             arg = {}
 
-        # Allows the underlying dict class to handle the arg as it usually would
+        # Allows the underlying dict class to handle the arg
+        # as it usually would
         super(ObjectDict, self).__init__(arg)
 
-        for (k, v) in self.items():
+        for k, v in self.items():
             self[k] = ObjectDict(v)
 
     def __delattr__(self, name):