Enable devel pipeline (#344)

- runs devel testing on CI
- install ansi2html and pytest-rerunfailures from git
- temporary disable pytest install from git due to known bug

Author: ssbarnea

.github/workflows/tox.yml

@@ -27,6 +27,8 @@ jobs:
             python-version: 3.7
           - name: py38
             python-version: 3.8
+          - name: devel
+            python-version: 3.8
           - name: pypy3
             python-version: pypy3
     steps:

tox.ini

@@ -27,7 +27,11 @@ basepython = python3
 pip_pre = True
 deps =
     {[testenv]deps}
-    pytest @ git+https://github.com/pytest-dev/pytest.git
+    ansi2html @ git+https://github.com/pycontribs/ansi2html.git
+    pytest-rerunfailures @ git+https://github.com/pytest-dev/pytest-rerunfailures.git
+    # Temporary disable pytest git install due to
+    # https://github.com/pytest-dev/pytest-rerunfailures/issues/134
+    # pytest @ git+https://github.com/pytest-dev/pytest.git
 
 [flake8]
 max-line-length = 88