Add check in pipeline to validate that `date` is the same as `dt-published`
As it would've flagged up #736 (closed), and shouldn't be a thing I want, anyway
Looks like quite a few affected:
-2019-07-18T18:20:56+0200
+2019-07-18 18:20:56+0200
Need to investigate whether this is expected/required.
Edited by Jamie Tanna