QUAL Force subclass MINVERSION (#26314)

* Define DoliDB::VERSIONMIN as mandatory constant in subclass

See https://stackoverflow.com/a/43134924/6378634

This also helps static tool checks

* fixup! Define DoliDB::VERSIONMIN as mandatory constant in subclass

htdocs/core/db/DoliDB.class.php

@@ -29,7 +29,9 @@ require_once DOL_DOCUMENT_ROOT.'/core/db/Database.interface.php';
  */
 abstract class DoliDB implements Database
 {
-	/** @var bool|resource|mysqli|SQLite3|PgSql\connection Database handler */
+	/** @var string Force subclass to implement VERSIONMIN */
+	const VERSIONMIN=self::VERSIONMIN;
+	/** @var bool|resource|mysqli|SQLite3|PgSql\Connection Database handler */
 	public $db;
 	/** @var string Database type */
 	public $type;