style: format code with Ktlint

This commit fixes the style issues introduced in 2c372a8 according to the output
from Ktlint.

Details: None

src/main/kotlin/org/example/Rover.kt

@@ -9,8 +9,8 @@ class Rover {
                     positionX = command[ROVER_STARTING_POSITION_X].toInt(),
                     positionY = command[ROVER_STARTING_POSITION_Y].toInt(),
                     heading =
-                        Heading.from(command[ROVER_FACING_DIRECTION][ROVER_COMMANDLIST_DIRECTION])
-                            ?: state.heading,
+                    Heading.from(command[ROVER_FACING_DIRECTION][ROVER_COMMANDLIST_DIRECTION])
+                        ?: state.heading,
                 )
         }
     }