Update "User-Agent" setting to more recent browser versions

Problem/Motivation

Please update the browser versions to a more recent version. The versions are quite outdated and we are trying to trick some site owners with this setting. The more often we are changing it the better as it becomes impossible to them to track us as a link checker tool.

theregister.com seem to detect the old Drupal agent from D7 as per today... I'm not sure about Guzzle yet, but we should not help them detecting the module.

Steps to reproduce

Proposed resolution

Update browser version strings to latest versions on market.

Remaining tasks

User interface changes

API changes

Data model changes