Allowed to add contact who's names are all numbers

[nus-pe-bot]

Can specify the contact's name to be solely numbers which is weird

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_{[original: nus-cs2103-AY2122S1/pe-interim#268] [original labels: severity.Low type.FunctionalityBug]}

[pualixue]

Team's Response

There might be names that contain numbers, e.g. Elon Musk's child. We have to include these cases too.

Duplicate status (if any):

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