Marked payedAmount as optional during creation and/or update

ref #193

src/models/actions/update/UpdateDonation.ts

@@ -1,4 +1,4 @@
-import { IsInt, IsPositive } from 'class-validator';
+import { IsInt, IsOptional, IsPositive } from 'class-validator';
 import { getConnection } from 'typeorm';
 import { DonorNotFoundError } from '../../../errors/DonorErrors';
 import { Donation } from '../../entities/Donation';
@@ -27,7 +27,8 @@ export abstract class UpdateDonation {
      * The donation's payed amount in the smalles unit of your currency (default: euro cent).
      */
     @IsInt()
-    payedAmount: number;
+    @IsOptional()
+    payedAmount?: number;
 
     /**
      * Creates a new Donation entity from this.