images: Pre-install glib-networking on bootc

cockpit-project/cockpit#21561 dropped
cockpit-bridge's glib-networking dependency. But two cockpit tests want
to install cockpit-ws, which still depends on glib-networking.
So put it back manually.

images/scripts/lib/bootc.Containerfile

@@ -3,10 +3,12 @@ FROM $base_image
 
 # pre-install the distro version, which is useful for testing extensions and manual experiments
 # also pre-install ws and test dependencies
+# also install glib-networking, so that tests can install cockpit-ws (as long as it has that dependency)
 RUN \
     dnf update -y --exclude='kernel*' && \
     dnf install -y --setopt install_weak_deps=False cockpit-system cockpit-networkmanager && \
     dnf install -y dnsmasq pcp python3-pcp rsync sscg strace system-logos wireguard-tools && \
+    dnf install -y glib-networking && \
     dnf clean all
 
 ADD lib/mcast1.nmconnection /usr/lib/NetworkManager/system-connections/