Change fk constraint in possible_date migration

data/migrations/20200502193352_possible_date.js

@@ -1,10 +1,9 @@
 exports.up = (knex) => {
 	return knex.schema.createTable('possible_date', (table) => {
 		table.increments('id').primary();
+		table.uuid('meeting_id').unsigned().notNullable();
 		table
-			.uuid('meeting_id')
-			.unsigned()
-			.notNullable()
+			.foreign('meeting_id')
 			.references('meeting.id')
 			.onDelete('cascade');
 		table.date('possible_date').notNullable();