Fix an attribute naming issue in crudkit. SQLAlchemy reserves the name "metadata."

crudkit/core/base.py

@@ -23,4 +23,4 @@ class Version(Base):
     timestamp = Column(DateTime, default=func.now())
 
     actor = Column(String, nullable=True)
-    metadata = Column(JSON, nullable=True)
+    meta = Column('metadata', JSON, nullable=True)

crudkit/core/service.py

@@ -98,7 +98,7 @@ class CRUDService(Generic[T]):
             change_type=change_type,
             data=data,
             actor=str(actor) if actor else None,
-            metadata=metadata
+            meta=metadata
         )
         self.session.add(version)
         self.session.commit()