appveyor: test_req path

Author: smurfix

.appveyor.yml

@@ -16,7 +16,7 @@ build_script:
   - "python --version"
   - "python -c \"import struct; print(struct.calcsize('P') * 8)\""
   - "pip install ."
-  - "pip install -Ur test-requirements.txt"
+  - "pip install -Ur ci/test-requirements.txt"
   - "pip install codecov"
 
 test_script: