Your Composer dependencies require a PHP version ">= 7.4.0". You are running 7.3.29

In you project you can check the platform check file projec-path/vendor/composer/platform_check.php

$issues = array();

      after this Remove or comment the extra code

2. Add the platform check option in the composer.json config section like this.

   "config": { "platform-check": false }

         After that, you need to run

      composer update

         After the composer update platform_check.php will be deleted and project work fine.