Explicitly coerce TargetPublishDate into ISO8601 prior to use in json

[riverar]

Resolves #179

[HowardWolosky]

Per the comments I added in #179, I'm not able to repro this problem. Before I'd take a change to the code, I'd like to better understand why we're seeing a difference in behavior. I'm going to close this PR down for now and we can continue the discussion via #179 until such time as we understand why you're seeing this problem and we're not.

[riverar]

@HowardWolosky If you're starting to ramp up PowerShell Core support, you may want to revisit this PR.

Per #179 (comment), I suspect you're going to run into some date/time issues soon.

[HowardWolosky]

Thanks for reminding me about this, @riverar. At the time that you brought up these issues, I didn't have a good understanding of PowerShell Core and its future/direction. I've been working with it quite a bit over in PowerShellForGitHub lately, so now I just have my head wrapped around it better. Especially with the advent of GitHub Actions (which use PS Core), it makes a lot more sense now to make sure that this is working in all PS environments.

[HowardWolosky]

Thanks for catching this, @riverar! Much appreciated.
The same change needs to be made on the IAP side as well. Would you mind doing that as well? Then I can get this submitted and get a new version released.

I've confirmed that there aren't any other places that are similarly affected.

[riverar]

Just got the alert on this, oddly. Will get this done by EOB.

[HowardWolosky]

Will get this done by EOB.

Thanks so much!

[HowardWolosky]

Thanks SO MUCH for catching the problem and submitting the fix! Much appreciated!