anagram: sync

[ErikSchierboom]

Sync the anagram exercise with the latest data, as defined in https://github.com/exercism/problem-specifications/tree/main/exercises/anagram.

• Feel free to close this PR if there is another PR that also syncs this exercise.
• When approved, feel free to merge this PR yourselves (you don't have to wait for me).

As this PR only updates docs and/or metadata, it won't trigger a re-run of existing solutions (see the docs).

[BNAndras]

CI failed here for nucleotide-count. I updated the exercise in #241 and it passes there so I'll go ahead and merge.