P5-6493 add vat to new markets model in api2 (#31)

api/models/market.py

@@ -10,6 +10,7 @@ class Market(db.Model):
 
     id = db.Column(db.Integer, primary_key=True)
     name = db.Column(db.String(255))
+    vat = db.Column(db.Float, nullable=False)
 
     @validates("name")
     def validate_name(self, key, value):
@@ -19,6 +20,7 @@ class Market(db.Model):
         return {
             "id": self.id,
             "name": self.name,
+            "vat": str(self.vat),
         }