refactor: Put a default value to options

Co-authored-by: Pierre Camilleri <[email protected]>

src/frformat/enum_format.py

@@ -11,8 +11,8 @@ class EnumFormat(CustomStrFormat):
 
         May preprocess the input and valid values according to given "options"."""
 
-        def __init__(self, options: Optional[Options] = None):
-            self.options = options if options is not None else Options()
+        def __init__(self, options: Options = Options()):
+            self.options = options
 
             _normalized_extra_values = {
                 normalize_value(e, self.options)