Selenium is using Firefox 47.0

prove -r t/db_dependent/selenium/

In parallel, check the access logs with koha-plack-log

"Mozilla/5.0 (X11; Linux x86_64; rv:47.0) Gecko/20100101 Firefox/47.0"

Firefox 47 is from June 7, 2016. That can definitely cause issues right?

Same for the version of Selenium. https://github.com/SeleniumHQ/docker-selenium/tree/2.53.1-americium