Add ISO date support

[mrcgrtz]

Allow either a relative numeric value or an ISO date string as values for the --expires flag:

1. --expires 20 sets an expiration date 20 days from now
2. --expires 2022-07-30T00:00:00Z sets July 7th, 2022 at 12am GMT as the expiration date

[coveralls]

Pull Request Test Coverage Report for Build 2755909874

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

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Details

• 13 of 13 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 2735501875:	0.0%
Covered Lines:	145
Relevant Lines:	145

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💛 - Coveralls