Use validator instead of moment to validate dates

[elaygl]

All Submissions:

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Have you written unit tests?
• Have you written unit tests that cover the negative cases (i.e.: if bad data is submitted, does the library respond properly)?
• This PR is associated with an existing issue?

Closing issues

closes #988

If this is a new feature submission:

• Has the issue had a maintainer respond to the issue and clarify that the feature is something that aligns with the goals and philosophy of the project?

Potential Problems With The Approach

None.

Test plan

The existing tests should cover this change.

[SteveVaknin]

LGTM 👌

[WoH]

LGTM