WIP: Pull in pygobject as a Debian package dependency

Create the venv with --system-site-packages so system python3-* packages
can be used.

debian/control

@@ -14,7 +14,7 @@ Description: securedrop client for qubes workstation
 
 Package: securedrop-export
 Architecture: amd64
-Depends: ${misc:Depends}, python3, udisks2, cups, cups-ipp-utils, printer-driver-brlaser, printer-driver-hpcups,
+Depends: ${misc:Depends}, python3, python3-gi-cairo, udisks2, cups, cups-ipp-utils, printer-driver-brlaser, printer-driver-hpcups,
  avahi-daemon, system-config-printer, libcups2, gnome-disk-utility, libreoffice,
  desktop-file-utils, shared-mime-info, libfile-mimeinfo-perl, gir1.2-gtk-4.0
 Description: Submission export scripts for SecureDrop Workstation

debian/setup-venv.sh

@@ -3,7 +3,7 @@
 set -euxo pipefail
 
 NAME=$1
-if [[ $NAME == "client" ]]; then
+if [[ $NAME == "client" || $NAME == "export" ]]; then
     VENV_ARGS="--system-site-packages"
 else
     VENV_ARGS=""

export/build-requirements.txt

@@ -1,4 +1,2 @@
 pexpect==4.9.0 --hash=sha256:5760fc48f9eb64fabd910e0b8f16b4c831e3ede32a3059ef7252e89a38950646
 ptyprocess==0.7.0 --hash=sha256:320c49e0aea7441a2e2a47bfc655442f1c4e9d27dc8cf2b905832934af942761
-pycairo==1.27.0 --hash=sha256:43b8f610ef329dfbc0a9431cc174044c52b78c6e02a5d2842c67edba1c10a51c
-pygobject==3.50.0 --hash=sha256:cb02f8b467eab914788fee782a66e79e7d3599821e3279298bb2a27089288138