.gitlab-ci.yml: Use distro packages instead pip to install sphinx
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 26e4f22..5eac5ad 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -136,8 +136,7 @@
   stage: test
   script:
   - dnf install -y python2
-  - pip3 install sphinx
-  - pip3 install sphinx-click
+  - dnf install -y sphinx python-sphinx-click
   - cd dist && ./unpack.sh && cd buildstream
   - pip3 install .
   - make -C doc