Fix tests referencing 'ajv8'

Author: nickgros

packages/playground/package-lock.json

@@ -1,5 +1,5 @@
-import Ajv from "ajv8";
-import Ajv2019 from "ajv8/dist/2019";
+import Ajv from "ajv";
+import Ajv2019 from "ajv/dist/2019";
 import addFormats from "ajv-formats";
 
 import createAjvInstance, {
@@ -9,8 +9,8 @@ import createAjvInstance, {
 } from "../src/createAjvInstance";
 import { CustomValidatorOptionsType } from "../src";
 
-jest.mock("ajv8");
-jest.mock("ajv8/dist/2019");
+jest.mock("ajv");
+jest.mock("ajv/dist/2019");
 jest.mock("ajv-formats");
 
 export const CUSTOM_OPTIONS: CustomValidatorOptionsType = {