Revert "donot test docs in tox"

This reverts commit ae109fc2

.gitlab-ci.yml

@@ -17,14 +17,6 @@ check-setup:
     script: 
         - pip install -U tox tox-pyenv
 
-#docs:
-#    stage: extra
-#    script:
-#        - tox -v -e docs
-py35:
-    stage: test
-    script:
-        - tox -v -e py35
 py36:
     stage: test
     script:     
@@ -37,7 +29,3 @@ py38:
     stage: test
     script:
         - tox -v -e py38
-py39:
-    stage: test
-    script:
-        - tox -v -e py39