deactivate volumes: terminate error message with newline

Avoid that Perl auto-attaches the line number and file name.

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Link: https://lore.proxmox.com/20250801081649.13882-1-f.ebner@proxmox.com

src/PVE/Storage.pm

@@ -1429,7 +1429,7 @@ sub deactivate_volumes {
         }
     }
 
-    die "volume deactivation failed: " . join(' ', @errlist)
+    die "volume deactivation failed: " . join(' ', @errlist) . "\n"
         if scalar(@errlist);
 }