Pin down twisted on Ubuntu Focal

install.sh

@@ -277,6 +277,12 @@ EOF
       funkwhale_systemd_managed: false
 EOF
     fi
+		if [ "$(lsb_release -sc)" = "focal" ]; then
+			cat <<EOF >>playbook.yml
+      funkwhale_custom_pip_packages:
+        - twisted==22.4.0
+EOF
+		fi
     cat <<EOF >reconfigure
 #!/bin/sh
 # reapply playbook with existing parameter