[BUGFIX] Change TYPO3_MODE to TYPO3

Configuration/TCA/Overrides/sys_template.php

 <?php
-defined('TYPO3_MODE') or die();
+defined('TYPO3') or die();
 
 \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addStaticFile(
     'randombanners',

Configuration/TCA/Overrides/tt_content.php

 <?php
-defined('TYPO3_MODE') or die();
+defined('TYPO3') or die();
 
 \TYPO3\CMS\Extbase\Utility\ExtensionUtility::registerPlugin(
     'Randombanners',

Configuration/TCA/tx_randombanners_domain_model_banner.php

 <?php
-defined('TYPO3_MODE') or die();
+defined('TYPO3') or die();
 
 \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::allowTableOnStandardPages('tx_randombanners_domain_model_banner');