`Refactor dataSchema.py: update class definitions and add docstring`

dataSchema.py

@@ -139,7 +139,7 @@ class service(BaseModel):
     rate: float = Field(..., description="the rate of the service.")
     total: float = Field(...,description="total which is the rate* No of days/hours .")
     
-class bank_details:
+class bank_details(BaseModel):
     bank_name: str = Field(..., description="Name of the bank.")
     swift_bic_code: str = Field(None, description=" SWIFT/BIC CODE.")
     iban_number: str = Field(...,description="IBAN Number.")
@@ -165,7 +165,6 @@ class Noc_Invoice(BaseModel):
     second_details : List[bank_details]=Field(...,description="second bank details") 
     
 
-
 Noc_timesheet_prompt = """
 Based on the provided timesheet details, extract the following information:
 - Position title of the person.