fix: remove Ubuntu 23.04 from CI

and disable by default in Vagrant, as addon installation is broken at
the moment for reasons outside of our control.

.github/workflows/ci.yml

@@ -17,7 +17,9 @@ jobs:
           - debian:11
           - debian:12
           - ubuntu:22.04
-          - ubuntu:23.04
+          # XXX addon installation is currently broken in Ubuntu 23.04 due to
+          # issues upstream of this role.  Omit from the workflow for now.
+          #- ubuntu:23.04
     container:
       image: ${{ matrix.image }}
     steps:

Vagrantfile

@@ -47,6 +47,11 @@ Vagrant.configure(2) do |config|
 
   config.vm.define :ubuntu2304 do |ubuntu2304|
     ubuntu2304.vm.box = 'generic/ubuntu2304'
+
+    # XXX addon installation is currently broken in Ubuntu 23.04 due to issues
+    # upstream of this role.  Do not bring up this machine by default.
+    ubuntu2304.autostart = false
+    ubuntu2304.primary = false
   end
 
   config.vm.define :libreelec do |libreelec|