Fix 3.7 broken pipeline again2

.gitlab-ci.yml

@@ -17,7 +17,7 @@
       - pip install flake8
       - pip install jinja2
       - pip install reportlab==3.6.6  # Freeze reportlab version because of https://github.com/xhtml2pdf/xhtml2pdf/issues/589
-      - pip install xhtml2pdf
+      - pip install 'xhtml2pdf==0.2.10'
       - pip install Markdown
       - pip install Pillow
       - pip install aiosmtplib