CI: urgh. So much time wasted debugging this *again*

.ci/test_template.sh

@@ -2,6 +2,11 @@
 
 source /test.venv/bin/activate
 
+apt install -y locales
+locale-gen en_US.UTF-8
+locale-gen en_GB.UTF-8
+update-locale
+
 # If running on a fork repository, we merge in the
 # upstream/master branch. This is done so that merge
 # requests from fork to the parent repository will