Bootstrap newer setuptools due to long_description_content_type.

Author: oohlaf

.appveyor/appveyor-bootstrap.py

@@ -117,4 +117,4 @@ def install_packages(home, *packages):
 if __name__ == "__main__":
     install_python(environ['PYTHON_VERSION'], environ['PYTHON_ARCH'], environ['PYTHON_HOME'])
     install_pip(environ['PYTHON_HOME'])
-    install_packages(environ['PYTHON_HOME'], "setuptools>=18.0.1", "wheel")
+    install_packages(environ['PYTHON_HOME'], "setuptools>=36.4.0", "wheel")