allow user to add task with deadline which is in the past

[nus-pe-bot]

the program allows user to add or edit the deadline to be as a date in the past.

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_{[original: nus-cs2103-AY2223S1/pe-interim#5672] [original labels: type.FeatureFlaw severity.Low]}

[XenonShawn]

Team's Response

Sometimes we overshoot a deadline. It is good that user can still put a deadline in the past. Blocking past deadlines does not make the feature more useful for the users, so we are rejecting this feature flaw.

Duplicate status (if any):

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