update template (Azure#23333)

* Update README.md

* Update setup.py

Author: msyyc

tools/azure-sdk-tools/packaging_tools/templates/README.md

@@ -1,7 +1,7 @@
 # Microsoft Azure SDK for Python
 
 This is the Microsoft Azure {{package_pprint_name}} Client Library.
-This package has been tested with Python 3.7+.
+This package has been tested with Python 3.6+.
 For a more complete view of Azure libraries, see the [azure sdk python release](https://aka.ms/azsdk/python/all).
 
 ## _Disclaimer_

tools/azure-sdk-tools/packaging_tools/templates/setup.py

@@ -49,7 +49,7 @@
     classifiers=[
         '{{classifier}}',
         'Programming Language :: Python',
-        "Programming Language :: Python :: 3 :: Only",
+        'Programming Language :: Python :: 3 :: Only',
         'Programming Language :: Python :: 3',
         'Programming Language :: Python :: 3.6',
         'Programming Language :: Python :: 3.7',