Merge pull request #423 from StephenBrown2/patch-1

Add python_requires to setup.py to fix #421

Author: insspb

setup.py

@@ -44,6 +44,7 @@ def get_version(version_tuple):
     author_email="ross.lawley@gmail.com",
     zip_safe=False,
     platforms="any",
+    python_requires=">=3.6",
     install_requires=[
         "Flask>=1.1.2",
         "WTForms[email]>=2.3.1",