Attempt at fixing recent build failures on AppVeyor

tleonhardt · tleonhardt · commit d914c8a544be · 2019-05-13T22:46:55.000-04:00
diff --git a/.appveyor.yml b/.appveyor.yml
@@ -1,7 +1,8 @@
-install:
-  - python -m pip install tox
-
 build: off
 
+install:
+  - python -m pip install -U pip
+  - python -m pip install -U wheel setuptools tox
+
 test_script:
   - python -m tox -e py35,py36,py37
