Sync Grains

[A-O-Emmanuel]

• Ran bin/configlet to update markdown instructions and test metadata
• Dropped strict types comments from test file and example code
• Raise the difficulty level
• Add exercise to bin/auto-sync.txt to keep it in sync
• Adjusted and ordered test cases to match current problem specs

[github-actions]

This PR touches files which potentially affect the outcome of the tests of an exercise. This will cause all students' solutions to affected exercises to be re-tested.

If this PR does not affect the result of the test (or, for example, adds an edge case that is not worth rerunning all tests for), please add the following to the merge-commit message which will stops student's tests from re-running. Please copy-paste to avoid typos.

[no important files changed]

For more information, refer to the documentation. If you are unsure whether to add the message or not, please ping @exercism/maintainers-admin in a comment. Thank you!

[mk-mxp]

Thanks a lot for this work!

[mk-mxp]

Thanks for your contribution!