exercises(sieve): sync docs

[ErikSchierboom]

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

• 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).

[ee7]

$ git rev-parse --short HEAD
e0f3d93c
$ bin/configlet sync -e sieve
Updating cached 'problem-specifications' data...
Checking exercises...
The `sieve` exercise has up-to-date docs, filepaths, metadata, and tests!