Update Maven version, Maven plugins and dependencies

- Update Maven to latest version (3.8.1).
- Update plugins to latest version (except for Jetty as we don't run latest version on our server).
- Set the version for Maven release plugin.
- Update dependencies to latest version (only patch version increase). Don't update Jetty (same motivation as above).
7 jobs for maven-updates in 3 minutes and 17 seconds (queued for 1 minute and 1 second)