Motor error handling bug

[pascalzauberzeug]

The motor error flags introduced in PR #68 are inside a set in double_wheels.py.
This causes the field friend hardware initialization to fail, because it expects a list of strings.

rosys_1       | 2024-06-24 11:05:53.086 [ERROR] field_friend/system.py:43: failed to initialize FieldFriendHardware rb36
rosys_1       | Traceback (most recent call last):
rosys_1       |   File "/app/field_friend/system.py", line 41, in __init__
rosys_1       |     self.field_friend = FieldFriendHardware()
rosys_1       |                         ^^^^^^^^^^^^^^^^^^^^^
rosys_1       |   File "/app/field_friend/hardware/field_friend_hardware.py", line 374, in __init__
rosys_1       |     super().__init__(implement_name=implement,
rosys_1       |   File "/app/field_friend/hardware/field_friend.py", line 42, in __init__
rosys_1       |     super().__init__(**kwargs)
rosys_1       |   File "/app/rosys/hardware/robot.py", line 32, in __init__
rosys_1       |     self.robot_brain.lizard_code = self.generate_lizard_code()
rosys_1       |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^
rosys_1       |   File "/app/rosys/hardware/robot.py", line 48, in generate_lizard_code
rosys_1       |     core.output("core.millis {' '.join(output_fields)}")
rosys_1       |                               ^^^^^^^^^^^^^^^^^^^^^^^
rosys_1       | TypeError: sequence item 2: expected str instance, set found

[pascalzauberzeug]

Fixed with #91