Fix the broken `httpcomponents-client` link.

[mashhurs]

Issue description

We have a deep explanation about validate_after_inactivity which also covers the apache http client internal details. This detail forwards to the apache website which is broken (404 page).

Fix

The plugin uses manticore (>= 0.8.0, < 1.0.0) and it seems it pulls the v0.9.1 where httpcomponents-client-4.5.13 will be included. We can forward to the link for this version.