[perfect-numbers] Add a Jinja test template

[IsaacG]

This updates the error message to match the problem specs, breaking existing solutions.

[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!

[kotp]

Is the solution file, the example file, that no longer is correct for the change in the generated test?

[IsaacG]

Is the solution file, the example file, that no longer is correct for the change in the generated test?

bash had "natural numbers". The problem spec has "positive integers". I accidentally changed the example solution from "natural numbers" to "positive numbers", correcting one of the two words.

The example is now in sync with the problem specs.

[kotp]

Looking good, passing all tests.