polari: unbreak

The build was failing due to missing telepathy_logger dependency,
I added it. Additionally, the connection to server was failing due to
telepathy executables not having an access to dconf, which was fixed
in #26113. Lastly, when I tried running Polari directly, it terminated
with SIGTRAP and the following error:

    (org.gnome.Polari:22998): GLib-GIO-ERROR **: Settings schema 'org.gnome.desktop.interface' is not installed

adding `gnome3.gsettings_desktop_schemas` as a buildInput fixed that.