Added pip installation in appveyor builds

.ci/install-pip.sh

@@ -0,0 +1,4 @@
+#!/bin/sh
+curl -O https://bootstrap.pypa.io/get-pip.py
+python3 get-pip.py
+rm -f get-pip.py

appveyor.yml

@@ -28,7 +28,6 @@ init:
     -P git \
     -P wget \
     -P curl
-  - "%CYG_BASH% -lc 'pip install cpp-coveralls'"
 
 environment:
   global:
@@ -60,6 +59,10 @@ install:
 build_script:
   - '%CYG_BASH% -lc "cd $APPVEYOR_BUILD_FOLDER; exec 0</dev/null; make"'
 
+before_test:
+  - "%CYG_BASH% -lc 'cd $APPVEYOR_BUILD_FOLDER; .ci/install-pip.sh'"
+  - "%CYG_BASH% -lc 'pip install cpp-coveralls'"
+
 test_script:
   - '%CYG_BASH% -lc "cd $APPVEYOR_BUILD_FOLDER/samples; exec 0</dev/null; make check"'