fixes #2296 include the correct class file depending on the version of php

include/pwgsession_php7.class.php

@@ -0,0 +1,34 @@
+<?php
+// see https://php.watch/versions/8.4/session_set_save_handler-alt-signature-deprecated
+// https://github.com/Piwigo/Piwigo/issues/2296
+class PwgSession implements SessionHandlerInterface {
+  public function open($path, $name)
+  {
+    return pwg_session_open($path, $name);
+  }
+
+  public function close()
+  {
+    return pwg_session_close();
+  }
+
+  public function read($id)
+  {
+    return pwg_session_read($id);
+  }
+
+  public function write($id, $data)
+  {
+    return pwg_session_write($id, $data);
+  }
+
+  public function destroy($id)
+  {
+    return pwg_session_destroy($id);
+  }
+
+  public function gc($max_lifetime)
+  {
+    return pwg_session_gc();
+  }
+}