sync: Update tests.toml if the corresponding canonical-data.json alters a test's description

[ee7]

Example

1. Say that a track has implemented an exercise bob, which has an up-to-date tests.toml file.
2. Change the description of a test in the canonical-data.json of that exercise in exercism/problem-specifications (assuming that we decide that the description is mutable).
3. Run configlet sync -u --tests

Current behaviour

The tests.toml file is not changed.

Expected behaviour

The tests.toml file should contain the new description

Context

See exercism/problem-specifications#1687 (comment).

@ee7 wrote:

Should it update the tests.toml file to overwrite the comment that contains the description?"
I think the answer is yes, but it currently doesn't.

@iHiD wrote:

If we went down the mutable route, then yes it should.

[ErikSchierboom]

Agreed!