Use https://grpc.io consistently as the canonical URL
diff --git a/setup.py b/setup.py
index 8ca3e4f..e42c834 100644
--- a/setup.py
+++ b/setup.py
@@ -281,7 +281,7 @@
   description='HTTP/2-based RPC framework',
   author='The gRPC Authors',
   author_email='grpc-io@googlegroups.com',
-  url='http://www.grpc.io',
+  url='https://grpc.io',
   license=LICENSE,
   long_description=open(README).read(),
   ext_modules=CYTHON_EXTENSION_MODULES,