requirements: py2exe only on win32 platform

requirements-dev.txt

@@ -25,7 +25,7 @@ grip==4.5.2
 #	<https://pip.pypa.io/en/stable/user_guide/#requirements-files>
 #	<https://pip.pypa.io/en/stable/reference/pip_install/#vcs-support>
 #py2exe==0.10.0.1
-git+https://github.com/albertosottile/py2exe.git@v0.10.0.1#egg=py2exe
+git+https://github.com/albertosottile/py2exe.git@v0.10.0.1#egg=py2exe; sys_platform == 'win32'
 
 # All of the normal requirements
 -r requirements.txt