Use newer version of Python on AppVeyor

appveyor.yml

@@ -1,6 +1,11 @@
 # version string format -- This will be overwritten later anyway
 version: "{build}"
 
+# We need a more up to date pip because Python 2.7 is EOL soon
+init:
+  - set PATH=C:\Python35\Scripts;%PATH%
+
+
 branches:
   except:
     - /dev-travis.+/
@@ -62,7 +67,7 @@ matrix:
 
 
 install:
-  - ps: if (($env:CONFIGURATION) -eq "Debug" -And ($env:coverage) -eq "1" ) { python -m pip --disable-pip-version-check install codecov }
+  - ps: if (($env:CONFIGURATION) -eq "Debug" -And ($env:coverage) -eq "1" ) { pip --disable-pip-version-check install codecov }
   - ps: if (($env:CONFIGURATION) -eq "Debug" -And ($env:coverage) -eq "1" ) { .\misc\installOpenCppCoverage.ps1 }
 
 # Win32 and x64 are CMake-compatible solution platform names.