ci: drop py2 lxml, pull in jinja2

.github/workflows/build_test.sh

@@ -46,9 +46,9 @@ PACKAGES=(
     mount
     net-tools
     perl
-    python-lxml
     python3-evdev
     python3-lxml
+    python3-jinja2
     python3-pip
     python3-pyparsing
     python3-setuptools

.github/workflows/mkosi.yml

@@ -27,7 +27,7 @@ jobs:
     - uses: systemd/mkosi@v9
 
     - name: Install
-      run: sudo apt-get update && sudo apt-get install --no-install-recommends python3-pexpect
+      run: sudo apt-get update && sudo apt-get install --no-install-recommends python3-pexpect python3-jinja2
 
     - name: Symlink
       run: ln -s .mkosi/mkosi.${{ matrix.distro }} mkosi.default