Make Parameter.status, Parameter.valid_from, Parameter.valid_to and Parameter.description optional

Also a little tidying

setra_client/models.py

 """Models used by the client"""
 import datetime
 import json
-import typing
 from enum import Enum
-from typing import Optional, TypeVar, List
+from typing import Optional, List
 import pydantic
 
 
@@ -69,7 +68,7 @@ class Voucher(BaseModel):
     voucherdate: datetime.datetime
     exref: Optional[str]
     voucherno: int
-    transactions: typing.List[Transaction]
+    transactions: List[Transaction]
 
 
 class Batch(BaseModel):
@@ -79,11 +78,11 @@ class Batch(BaseModel):
     """
     client: str
     batchid: str
-    period: typing.Optional[str]
+    period: Optional[str]
     interface: str
-    vouchertype: typing.Optional[str]
-    batch_progress: typing.Optional[str]
-    vouchers: typing.Optional[typing.List[Voucher]]
+    vouchertype: Optional[str]
+    batch_progress: Optional[str]
+    vouchers: Optional[List[Voucher]]
 
 
 class ErrorTransaction(BaseModel):
@@ -114,9 +113,9 @@ class ErrorBatch(BaseModel):
 
 class BatchErrors(BaseModel):
     """Model for the /batch_error/<id> endpoint"""
-    batch_errors: typing.List[ErrorBatch]
-    voucher_errors: typing.List[ErrorVoucher]
-    transaction_errors: typing.List[ErrorTransaction]
+    batch_errors: List[ErrorBatch]
+    voucher_errors: List[ErrorVoucher]
+    transaction_errors: List[ErrorTransaction]
 
 
 class CompleteTransaction(BaseModel):
@@ -152,7 +151,7 @@ class CompleteVoucher(BaseModel):
     voucherno_ubw: Optional[int]
     voucherno_ubw_wflow: Optional[int]
     vouchertype: Optional[str]
-    transactions: typing.List[CompleteTransaction]
+    transactions: List[CompleteTransaction]
 
 
 class CompleteBatch(BaseModel):
@@ -176,7 +175,7 @@ class CompleteBatch(BaseModel):
     getresult_logg: Optional[str]
     getresult_report: Optional[str]
     batch_progress: str
-    vouchers: typing.List[CompleteVoucher]
+    vouchers: List[CompleteVoucher]
 
 
 class Parameter(BaseModel):
@@ -187,7 +186,7 @@ class Parameter(BaseModel):
     mandatory: str
     validation: str
     value: str
-    status: str
-    valid_from: datetime.date
-    valid_to: datetime.date
-    description: str
+    status: Optional[str]
+    valid_from: Optional[datetime.date]
+    valid_to: Optional[datetime.date]
+    description: Optional[str]

tests/fixtures/params.json

@@ -20,10 +20,10 @@
     "mandatory": "j",
     "validation": "j",
     "value": "wat",
-    "status": "anerikke",
-    "valid_from": "2020-01-01",
-    "valid_to": "2020-01-01",
-    "description": "Min parameter b"
+    "status": null,
+    "valid_from": null,
+    "valid_to": null,
+    "description": null
   },
   {
     "client": "72",