Update Generator.php

[spzgy]

In yii\db\BaseActiveRecord, there is no getTableSchema method. When using Gii to generate CRUD for non-relational databases, an error occurs because the getTableSchema method cannot be found.

Q	A
Is bugfix?	✔️/❌
New feature?	✔️/❌
Breaks BC?	✔️/❌
Fixed issues

[what-the-diff]

PR Summary

• Updated ActiveRecord Class in Generator
  The type of ActiveRecord we use in our 'Generator' code file has been updated. Instead of 'BaseActiveRecord', now 'ActiveRecord' is used which means we're accessing the more comprehensive functionality provided by ActiveRecord. This could potentially increase efficiency and manageability of the code.

[samdark]

Please add a line for CHANGELOG. Thanks.