fix: resolve a type error

#6443

npm/ng-packs/packages/schematics/src/utils/workspace.ts

@@ -1,8 +1,8 @@
-import { experimental, strings, workspaces } from '@angular-devkit/core';
+import { strings, workspaces } from '@angular-devkit/core';
 import { SchematicsException, Tree } from '@angular-devkit/schematics';
 import { Exception } from '../enums';
 import { Project } from '../models';
-import { getWorkspace, ProjectType } from './angular';
+import { getWorkspace, ProjectType, WorkspaceSchema } from './angular';
 import { findEnvironmentExpression } from './ast';
 import { readFileInTree } from './common';
 
@@ -23,7 +23,7 @@ export function readWorkspaceSchema(tree: Tree) {
   const workspaceBuffer = tree.read('/angular.json') || tree.read('/workspace.json');
   if (!workspaceBuffer) throw new SchematicsException(Exception.NoWorkspace);
 
-  let workspaceSchema: experimental.workspace.WorkspaceSchema;
+  let workspaceSchema: WorkspaceSchema;
 
   try {
     workspaceSchema = JSON.parse(workspaceBuffer.toString());