Phone Number broken tests fix

[TheRealOwenRees]

Fixed Phone Number exercise at #472

• deleted .broken file
• updated Example.re to pass tests correctly
• updated test template file to prevent nesting tests

This will affect the outcome of the tests of the exercise, with students needing to update to the latest exercise.

Resolves #472

[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!

[kahgoh]

Looks good! Thanks!