Disable correct PHP version for the system (#11 and #28)

lib/os/class.ISPConfigDebianOS.inc.php

@@ -158,7 +158,17 @@ class ISPConfigDebianOS extends ISPConfigBaseOS {
 	}
 
 	protected function getApacheModulesToDisable() {
-		$modules = array('php8.0', 'mpm_prefork');
+		$modules = array(
+			'mpm_prefork'
+		);
+
+		if(ISPConfig::wantsPHP() === 'system') {
+			array_unshift($modules, 'php' . $this->getSystemPHPVersion());
+		} else {
+			array_unshift($modules, 'php8.0');
+			);
+		}
+	}
 
 		return $modules;
 	}
@@ -804,6 +814,7 @@ mailman-unsubscribe:  "|/var/lib/mailman/mail/mailman unsubscribe mailman"';
 		if(ISPConfig::wantsPHP() === 'system') {
 			$php_versions = array($this->getSystemPHPVersion());
 		} else {
+			// If a new version is added, the getApacheModulesToDisable function should be updated to disable the latest version
 			$php_versions = array(
 				'5.6',
 				'7.0',