Quote class preference is not working

I want to overwrite validateMinimumAmount function that is available in MagentoQuoteModelQuote class.

Below is my di.xml

 <?xml version="1.0"?>

below is my preference class:

namespace MynameMinamountModel;

class Quote extends MagentoQuoteModelQuote
{

public function validateMinimumAmount($multishipping = false)
{

// here my logic is going
}
}

At the time of di compile it is showing below error:
Class ‘MynameMinamountModelMagentoQuoteModelQuote’ not found#

Magento version : 2.4.3-p1

Thanks