when i use select2 in yii2 form always show error like this:

Invalid Configuration – yiibaseInvalidConfigException
You must install ‘yiisoft/yii2-bootstrap’ extension for Bootstrap 3.x version support. Dependency to ‘yii2-bootstrap’ has not been included with ‘yii2-krajee-base’. To resolve, you must add ‘yiisoft/yii2-bootstrap’ to the ‘require’ section of your application’s composer.json file and then run ‘composer update’.

NOTE: This dependency change has been done since v2.0 of ‘yii2-krajee-base’ because only one of ‘yiisoft/yii2-bootstrap’ OR ‘yiisoft/yii2-bootstrap4’ OR ‘yiisoft/yii2-bootstrap5’ extensions can be installed. The developer can thus choose and control which bootstrap extension library to install.

I have taken steps to resolve the error but always experience the same error