Ordering pending publications

[abpolym]

Scenario:

• publication A has to_be_published = true, date = 2022-09-30 and publication_date = 2022-11-02 (example: Variational Bayes...)
• publication B has to_be_published = false, date = 2022-10-17 and publication_date is missing (example: Principled Pruning...)

Then publication A is ranked below B:

Since the publications should be ranked by publication date / time (descending: newest publications at the top), this is incorrect (to be published in November is below October, 2022) and has to be fixed.

Probably has to be changed here: https://github.com/biaslab/hugo-academic-group