.gitlab-ci.yml: build docs with python 3 instead

Fixes issues in the CI due to python 2 being EOL.

.gitlab-ci.yml

@@ -138,12 +138,13 @@ test:el7-python2:
   dependencies:
     - build:el7
   before_script:
+    - yum ${YUM_OPTS} remove python2-apipkg python36-apipkg
     - yum ${YUM_OPTS} install
           python-pytest
-          python-pytest-cov
+          python2-pytest-cov
     - yum ${YUM_OPTS} --nogpgcheck localinstall dist/el7/python2-ligo-scald-*.rpm
     - yum ${YUM_OPTS} --nogpgcheck localinstall dist/el7/ligo-scald-*.rpm
-    - pip install kafka-python confluent-kafka==0.11.5
+    - yum ${YUM_OPTS} install python2-confluent-kafka
   after_script:
     - scald --help
     - scald serve --help
@@ -164,11 +165,12 @@ test:el7-python3:
   variables:
     PYTHON: python3
   before_script:
+    - yum ${YUM_OPTS} remove python2-apipkg python36-apipkg
     - yum ${YUM_OPTS} install
-          python-pytest
-          python-pytest-cov
+          python36-pytest
+          python36-pytest-cov
     - yum ${YUM_OPTS} --nogpgcheck localinstall dist/el7/python36-ligo-scald-*.rpm
-    - python3 -m pip install kafka-python confluent-kafka==0.11.5
+    - yum ${YUM_OPTS} install python36-confluent-kafka
   cache:
     key: "${CI_JOB_NAME}"
     paths:
@@ -236,12 +238,15 @@ test:debian-python3:stretch:
 docs:
   stage: build
   image: igwn/software:el7
+  variables:
+    PYTHON: python3
   before_script:
-    - pip install dist/ligo-scald*.tar.gz
+    - ${PYTHON} -m pip install -U setuptools pip
+    - ${PYTHON} -m pip install dist/ligo-scald*.tar.gz
     - yum ${YUM_OPTS} install graphviz
-    - pip install sphinx==1.7.9 sphinxcontrib-programoutput sphinx_rtd_theme
+    - ${PYTHON} -m pip install sphinx==1.7.9 sphinxcontrib-programoutput sphinx_rtd_theme
   script:
-    - python -m sphinx -b html doc site -E
+    - ${PYTHON} -m sphinx -b html doc site -E
   artifacts:
     paths:
       - site