[add]: Loan charges model

app/models/loan_charge.py

@@ -1,5 +1,6 @@
 from datetime import datetime, timezone
 from app.extensions import db
+from app.models import LoanCharge
 from sqlalchemy.orm import relationship
 
 
@@ -23,6 +24,7 @@ class LoanCharge(db.Model):
         foreign_keys=[loan_id],
         back_populates="loan_charges",
     )
+
  
 
     def to_dict(self):