Update: Remove the 4th branch in favour of just making that the else branch

Probably easier to not have an "unused" branch that returns the same as the else branch in the example.

Signed-off-by: mikkurogue <mikkurogue@noreply.codeberg.org>

exercises/108_labeled_switch.zig

@@ -34,7 +34,6 @@
 //              1 => continue :foo 2,
 //              2 => continue :foo 3,
 //              3 => return,
-//              4 => {},
 //              else => {},
 //          }
 //          std.debug.print("This statement cannot be reached");