feat: v4.0.0 (#1016)

Co-authored-by: Denys Konovalov <kontakt@denyskon.de>
Co-authored-by: Mathieu COSYNS <64072917+Mathieu-COSYNS@users.noreply.github.com>

cypress/plugins/testBackend.ts

@@ -0,0 +1,13 @@
+import merge from 'lodash/merge';
+import { updateConfig } from '../utils/config';
+
+import type { Config } from '@staticcms/core/interface';
+import type { SetupBackendResponse } from '../interface';
+
+export async function setupTestBackend(options: Partial<Config>): Promise<SetupBackendResponse> {
+  await updateConfig(current => {
+    merge(current, options);
+  });
+
+  return null;
+}