🤖 Change difficulty 0 to 1

[ErikSchierboom]

Set difficulty to 1 for exercises which difficulty is currently 0.
See exercism/docs#290 and exercism/configlet#447.

Please feel free to update the difficulty to another value (the allowed range is 1-10) if you think that makes more sense.

[petertseng]

If difficulty is meaningless for deprecated exercises, the attribute should just be deleted for them, and configlet should not expect it to be present.

If difficulty is meaningful for deprecated exercises, the difficulty of the exercises should be restored to their pre-deprecation values.

[petertseng]

the difficulty of the exercises should be restored to their pre-deprecation values.

What I have asked is impossible. The deprecation of these excercises predates the concept of a difficulty value for exercises. In that case, take no further action and merge as-is.

[ErikSchierboom]

If difficulty is meaningful for deprecated exercises, the difficulty of the exercises should be restored to their pre-deprecation values.

It is indeed meaningful, as deprecated exercises were once active and any student that started the exercise before it was deprecated will still have access to it even after it was deprecated.