fix(enum): using wrong class when finding value (#19)

Author: portellaa

src/core/ydata/core/enum/string_enum.py

@@ -7,22 +7,22 @@ def _missing_(cls, value):
     if isinstance(value, str):
       upper_value = value.upper()
 
-      key = StringEnum._key_from_str_(upper_value)
+      key = cls._key_from_str(upper_value)
       if key is not None:
         return key
 
       lower_value = value.lower()
 
-      key = StringEnum._key_from_str_(lower_value)
+      key = cls._key_from_str(lower_value)
       if key is not None:
         return key
 
     raise ValueError(f"{value} is not a valid {cls.__name__}")
 
   @classmethod
-  def _key_from_str_(cls, value: str):
-    if value in cls.__members__:
-      return cls(value)
+  def _key_from_str(cls, value: str):
+    if value in cls._member_map_.keys():
+      return cls._member_map_[value]
 
     return None