Validate MF2 entries have the same Hugo date + MF2 date
As it was noticed as part of #736 (closed) that some of these dates were incorrect for steps data, I thought (as part of #738 (closed)) I should add a validation step within the pipeline to catch these issues before they can make it to production, where they risk impacting anyone.
Then, we need to align any content that isn't correct.
Closes #738 (closed).