WIP: Update Python packages and Bootstrap

[JoepdeJong]

• [ ] Update postgres
• [ ] Update elasticsearch (https://github.com/WISVCH/flux-beheer/blob/ae1e63180cf26ae1b50cda391a410d31b24fdfe4/dienst2/deploy.yaml) to use 7.x. (Haystack currently supports Elasticsearch 1.x, 2.x, 5.x, and 7.x.: https://django-haystack.readthedocs.io/en/latest/installing_search_engines.html#elasticsearch)

[JoepdeJong]

Resolves #266, #265

[praseodym]

This PR is outdated but still has some good changes, maybe we should cherry-pick those to several separate, smaller PRs?

[JoepdeJong]

This PR is outdated but still has some good changes, maybe we should cherry-pick those to several separate, smaller PRs?

yes, that was indeed my plan. i will make this branch up to date and use this code when we migrate to the cloud.