DateTimeFormat wrong

[macgills]

Summary:

Cannot save contribution on successful upload because format is not is08601 datetime

Steps to reproduce:

Attempt to upload anything, see failure.

System logs:

W/UploadService: Exception during upload
    java.text.ParseException: Unparseable date: "2020-04-07T14:16:51Z"
        at java.text.DateFormat.parse(DateFormat.java:362)
        at fr.free.nrw.commons.upload.UploadService.lambda$uploadContribution$5$UploadService(UploadService.java:290)

Commons app version:

master.

Would you like to work on the issue?

Yes

[sivaraam]

Just wanted to mention that this seems related to the change done in PR #3589