Minimum PHP version set to 7.4.

Unit test added for PHP 8.3

.github/workflows/test-unit.yml

@@ -16,11 +16,10 @@ jobs:
       fail-fast: false
       matrix:
         interpreter:
-          - image: php:5.6
-          - image: php:7.0
           - image: php:7.4
           - image: php:8.1
           - image: php:8.2
+          - image: php:8.3
         db:
           - image: mysql:5.5
           - image: bitnami/mysql:8.0

install.php

@@ -11,7 +11,7 @@
 */
 
 // minimal software version
-define('MIN_PHP_VERSION',   '5.6');
+define('MIN_PHP_VERSION',   '7.4');
 define('MIN_MYSQL_VERSION', '4.1.2');
 define('MAKE_INSTALL_LOG', true);