Merge pull request #4140 from Gallaecio/docs-py38

Use the latest Python version to build the documentation

.readthedocs.yml

@@ -0,0 +1,7 @@
+version: 2
+sphinx:
+  configuration: docs/conf.py
+python:
+  version: 3.8
+  install:
+    - requirements: docs/requirements.txt

.travis.yml

@@ -25,7 +25,7 @@ matrix:
     - env: TOXENV=extra-deps
       python: 3.8
     - env: TOXENV=docs
-      python: 3.6
+      python: 3.8
 install:
   - |
       if [ "$TOXENV" = "pypy3" ]; then

tox.ini

@@ -77,18 +77,21 @@ deps =
     -rdocs/requirements.txt
 
 [testenv:docs]
+basepython = python3
 changedir = {[docs]changedir}
 deps = {[docs]deps}
 commands =
     sphinx-build -W -b html . {envtmpdir}/html
 
 [testenv:docs-coverage]
+basepython = python3
 changedir = {[docs]changedir}
 deps = {[docs]deps}
 commands =
     sphinx-build -b coverage . {envtmpdir}/coverage
 
 [testenv:docs-links]
+basepython = python3
 changedir = {[docs]changedir}
 deps = {[docs]deps}
 commands =