Rework Expenses resource (#3)

Co-authored-by: Joe Arndt <jmarndt@users.noreply.github.com>
Reviewed-on: #3

src/expenses/dto/create-expense.dto.ts

@@ -0,0 +1,10 @@
+import { Category } from '../../categories/entities/category.entity';
+
+export class CreateExpenseDto {
+  year: string;
+  month: string;
+  day: string;
+  cents: number;
+  description: string;
+  category: Category
+}