fix(backend): error on node creation from root nodes (#445)

NodeType.ENTRY was not converted to its corresponding value

Author: perierc

backend/editor/models/node_models.py

@@ -2,13 +2,13 @@
 Required pydantic models for API
 """
 
-from enum import Enum
+from enum import StrEnum
 
 from .base_models import BaseModel
 from .types.datetime import DateTime
 
 
-class NodeType(str, Enum):
+class NodeType(StrEnum):
     TEXT = "TEXT"
     SYNONYMS = "SYNONYMS"
     STOPWORDS = "STOPWORDS"