Bring dependencies up to date

[kecnry]

Closes https://github.com/phoebe-project/phoebe-development/issues/111

[kecnry]

Thank you so much for doing this @matthiasfabry!

I ran into a few issues while testing that we should try to resolve before merging:

• anchor links seem to not be working, for example: https://phoebe-project.org/clients#desktop
• workshops page seems to be broken (possibly could be because of trying to load remote images from the server?)
• header links at the top of /docs is not loading the correct version string and pointing to /docs/null/tutorials, etc, instead
• publications subpages are broken (https://phoebe-project.org/publications/2005Prsa+, for example)
• dropdowns under "develop" and "help" in navbar are broken (perhaps because of missing jquery?)

[matthiasfabry]

These commits fix most of the problems mentioned above. Albeit with messing up the styling somewhat. I'm at a loss on how to style the NavLinks and the NavDropdown identically.
Also the workshop page indeed doesn't work because pictures are in /static/ somewhere. Are these not accessible?

[kecnry]

Yes, static files are hosted separately, so if the images are the only problem, that's probably ok. We can also try with the full absolute links instead to at least test if they're working