Update devise when version 5 is released

[RandomTannenbaum]

We currently use the newest version of devise, which is 4.9.4. Since version 8 of rails routes are lazy loaded by default. This does not work properly with the current devise version, since its mappings are built during the routes loading phase. For now we just fixed it by eager loading in the test environment. After the next devise release we should be able to disable eager loading again for the local test env.

See: heartcombo/devise#5728

ToDo

• Update devise
• Turn off eager loading for local test environment