Travis: build cp39 windows wheels

Author: edenhill

tools/wheels/build-wheels.bat

@@ -13,7 +13,7 @@ set WHEELHOUSE=%4
 if [%WHEELHOUSE%]==[] goto usage
 echo on
 
-set CIBW_BUILD=cp27-%BW_ARCH% cp36-%BW_ARCH% cp37-%BW_ARCH% cp38-%BW_ARCH% cp39-%BW_WARCH%
+set CIBW_BUILD=cp27-%BW_ARCH% cp36-%BW_ARCH% cp37-%BW_ARCH% cp38-%BW_ARCH% cp39-%BW_ARCH%
 set CIBW_BEFORE_BUILD=python -m pip install delvewheel==0.0.6
 set CIBW_TEST_REQUIRES=-r tests/requirements.txt
 set CIBW_TEST_COMMAND=pytest {project}\tests\test_Producer.py