pin PyGObject versions to distro provided packages

this prevents pip trying to build the pypi package and failing.
Fixes: #1107

installer/lib/requirements-ubuntu-bionic.apt

@@ -4,6 +4,8 @@ coreutils
 curl
 ecasound
 flac
+gcc
+gir1.2-gtk-3.0
 gstreamer1.0-plugins-bad
 gstreamer1.0-plugins-good
 gstreamer1.0-plugins-ugly
@@ -11,9 +13,12 @@ icecast2
 lame
 libao-ocaml
 libapache2-mod-php7.2
+libcairo2-dev
 libcamomile-ocaml-data
 libfaad2
 libffi-dev
+libglib2.0-dev
+libgirepository1.0-dev
 libmad-ocaml
 libopus0
 libportaudio2
@@ -48,22 +53,24 @@ php-apcu
 php-bcmath
 php-mbstring
 php-pear
+pkg-config
 postgresql
 postgresql-client
 pwgen
 python3
+python3-cairo
 python3-dev
+python3-gi
+python3-gi-cairo
 python3-gst-1.0
 python3-pika
 python3-pip
 python3-virtualenv
-python3-cairo
 rabbitmq-server
 silan
 sysvinit-utils
 unzip
 vorbisgain
 vorbis-tools
-vorbis-tools
 xmlstarlet
 zip