Update to 3.22.6:

* Fix minor memory leak [(#682723)](https://bugzilla.gnome.org/show_bug.cgi?id=682723)
* Fix serious password extraction sweep attack on password manager [(#752738)](https://bugzilla.gnome.org/show_bug.cgi?id=752738)
* Fix adblocker blocking too much stuff, breaking Twitter [(#777714)](https://bugzilla.gnome.org/show_bug.cgi?id=777714)