Remove pypiwin32 hard-coded dependency

Author: gonzalocasas

.travis.yml

@@ -9,7 +9,6 @@ matrix:
       before_install:
         - choco install python2 vcredist2008
         - choco install --ignore-dependencies vcpython27
-        - pip install pypiwin32
       env:
         - PATH=/c/Python27:/c/Python27/Scripts:$PATH
         - TRAVIS_PYTHON_VERSION=2.7
@@ -18,7 +17,6 @@ matrix:
       language: shell
       before_install:
         - choco install python
-        - pip install pypiwin32
       env:
         - PATH=/c/Python37:/c/Python37/Scripts:$PATH
         - TRAVIS_PYTHON_VERSION=3.7