api: types: CHANGER_DRIVENUM_SCHEMA: increase maximum drives per changer

to 255. 8 drives per changer was a rather arbitrary limitation and could
well be reached in practice with big libraries.

Altough 255 is still a arbirtrary limitation, this is much less likely
to be reached in practice.

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>

src/api2/types/tape/drive.rs

@@ -28,7 +28,7 @@ pub const LTO_DRIVE_PATH_SCHEMA: Schema = StringSchema::new(
 pub const CHANGER_DRIVENUM_SCHEMA: Schema = IntegerSchema::new(
     "Associated changer drive number (requires option changer)")
     .minimum(0)
-    .maximum(8)
+    .maximum(255)
     .default(0)
     .schema();