windows tends not to have python3 aliases

Author: djeebus

.appveyor.yml

@@ -22,7 +22,7 @@ install:
   - set PATH=C:\Python%PYTHON_MAJOR%%PYTHON_MINOR%;%PATH%
   - set PATH=C:\Python%PYTHON_MAJOR%%PYTHON_MINOR%\Scripts;%PATH%
   # Install system dependencies
-  - curl -sSL https://install.python-poetry.org | python3 -
+  - curl -sSL https://install.python-poetry.org | python -
   - make doctor
   # Install project dependencies
   - make install