WEB: Update RELEASE_DEBIAN to 1.8.1

According to the Debian website for the ScummVM
package [https://packages.debian.org/sid/scummvm],
the current version available in the "sid" repository
is 1.8.1.

include/config.inc.php

@@ -2,7 +2,7 @@
 /* Current version. */
 define('RELEASE', '1.8.1');
 define('RELEASE_TOOLS', '1.8.0');
-define('RELEASE_DEBIAN', '1.8.0');
+define('RELEASE_DEBIAN', '1.8.1');
 /* Version when the percentages on the compat page were removed */
 define('COMPAT_LAYOUT_CHANGE', '1.7.0');