CI(appveyor.yml): Upgrade `pip` using `python -m pip`

Avoid `WindowsError: [Error 5] Access is denied`.

diff --git a/appveyor.yml b/appveyor.yml
index 4b8ec355a3ffc5c2bd0050e44c24f3cf7d4fae44..a2f112bc8e1f6e598639b5db85ec5a1024d844e9 100644 (file)
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -49,8 +49,9 @@ install:
   - "SET TOXPYTHON=%PYTHON_HOME%\\python.exe"
   - "python --version"
   - "python -c \"import struct; print(struct.calcsize('P') * 8)\""
+  - "python -m pip install --upgrade pip setuptools"
+  - "pip install --upgrade tox"
   - "pip --version"
-  - "pip install --upgrade pip setuptools tox"
 
 # No build step - we don't have C extensions
 build: false