reqs: testing: unpin django-configurations/pytest-xdist (#645)

* reqs: testing: unpin django-configurations/pytest-xdist

* Travis: upgrade tox to 3.3.0

* Travis: tox: remove travis_retry_pip install wrapper

Author: blueyed

.travis.yml

@@ -72,18 +72,7 @@ stages:
     if: tag IS present
 
 install:
-  # Create pip wrapper script, using travis_retry (a function) and
-  # inject it into tox.ini.
-  - mkdir -p bin
-  - PATH=$PWD/bin:$PATH
-  - printf '#!/bin/sh\n' > bin/travis_retry_pip
-  - declare -f travis_retry >> bin/travis_retry_pip
-  - printf '\necho "Using pip-wrapper.." >&2\ntravis_retry pip "$@"' >> bin/travis_retry_pip
-  - chmod +x bin/travis_retry_pip
-  - sed -i.bak 's/^\[testenv\]/\0\nwhitelist_externals = travis_retry_pip\ninstall_command = travis_retry_pip install {opts} {packages}/' tox.ini
-  - if diff tox.ini tox.ini.bak; then exit 1; fi
-
-  - pip install tox==2.9.1
+  - pip install tox==3.3.0
   - |
     # Setup coverage tracking.
     if [[ "$SKIP_COVERAGE" != "1" ]]; then

setup.py

@@ -42,8 +42,8 @@ def read(fname):
         'testing': [
             'pytest>=3.6',
             'Django',
-            'django-configurations==2.0',
-            'pytest-xdist==1.15',
+            'django-configurations>=2.0',
+            'pytest-xdist>=1.15',
             'six',
         ],
     },