beer-song: update tests to canonical-data v2.0.0

[cmccandless]

Currently, the beer-song exercise does not reference the canonical data. The current tests must be checked and, if necessary, updated to match the canonical data. A comment line referencing the canonical data version must also be added (see #784 for the format of this comment).

[ajubin]

Hi, I'd like to contribute to this repo,
I've read the contributing guide, should I do a pull request directly once I fixed the issue ?

[cmccandless]

@ajubin This issue already has a PR (#1165). If you would like to contribute, please see the list of exercises with the help wanted label.