ZO-4513, ZO-859: Have to install lxml dependencies

I guess our lxml version is too old and doesn't vendor them
appropriately? In zeit.web which uses 5.x this works just fine out of
the box.

.github/workflows/testrunner.yaml

@@ -85,14 +85,15 @@ jobs:
       - uses: actions/[email protected]  # for jshint
         with:
           node-version: "20"
-      - name: setup gcc  # XXX for e.g. `pygraphviz`
+      - name: setup apt  # XXX gcc for e.g. `pygraphviz`
         # firefox dependencies see https://github.com/microsoft/playwright/blob/main/packages/playwright-core/src/server/registry/nativeDeps.ts
         run: |
             export DEBIAN_FRONTEND=noninteractive
             sudo apt-get update
             sudo apt-get -y install --no-install-recommends \
                 libasound2 libatk1.0-0 libcairo-gobject2 libcairo2 libdbus-1-3 libdbus-glib-1-2 libfontconfig1 libfreetype6 libgdk-pixbuf-2.0-0 libglib2.0-0 libgtk-3-0 libpango-1.0-0 libpangocairo-1.0-0 libx11-6 libx11-xcb1 libxcb-shm0 libxcb1 libxcomposite1 libxcursor1 libxdamage1 libxext6 libxfixes3 libxi6 libxrandr2 libxrender1 libxtst6 \
-                build-essential graphviz-dev
+                build-essential graphviz-dev \
+                libxml2 libxslt1.1
       - uses: browser-actions/[email protected]
         id: setup-firefox
       - name: setup geckodriver