Appveyor: Problem with dependencies

XMLBear is skipped on Appveyor Windows builds.
This installs dependencies for lxml.

Fixes coala#1354

.ci/appveyor.yml

@@ -40,6 +40,7 @@ install:
   # Check that we have the expected version and architecture for Python
   - "python --version"
   - "python -c \"import struct; print(struct.calcsize('P') * 8)\""
+  - "%CMD_IN_ENV% set STATICBUILD=true && pip install lxml"
 
   - "%CMD_IN_ENV% pip install wheel"
   # Create c:/wheels if it does not exist.