fix: creates restock functionality

packages/medusa-plugin-restock-notification/src/migrations/1617703530229-restock_notification.ts

@@ -0,0 +1,21 @@
+import { MigrationInterface, QueryRunner } from "typeorm"
+
+export class restockNotification1617703530229 implements MigrationInterface {
+  name = "restockNotification1617703530229"
+
+  public async up(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(
+      `CREATE TABLE "restock_notification" ("variant_id" character varying NOT NULL, "emails" jsonb NOT NULL, "created_at" TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT now(), "updated_at" TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT now(), CONSTRAINT "PK_49181ca04caac807fcec321705a" PRIMARY KEY ("variant_id"))`
+    )
+    await queryRunner.query(
+      `ALTER TABLE "restock_notification" ADD CONSTRAINT "FK_49181ca04caac807fcec321705a" FOREIGN KEY ("variant_id") REFERENCES "product_variant"("id") ON DELETE NO ACTION ON UPDATE NO ACTION`
+    )
+  }
+
+  public async down(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(
+      `ALTER TABLE "restock_notification" DROP CONSTRAINT "FK_49181ca04caac807fcec321705a"`
+    )
+    await queryRunner.query(`DROP TABLE "restock_notification"`)
+  }
+}