Add python3.9 support

This ps adds py39 support and replaces dashes with underscores

Change-Id: I5245be419244c8bd93c7099b61ce0a382f7a5065

Author: wchy1001

.gitignore

@@ -16,3 +16,6 @@ ChangeLog
 releasenotes/build
 /doc/build/
 /doc/source/reference/api/
+
+# Files generated by JetBrains
+.idea/

setup.cfg

@@ -1,12 +1,12 @@
 [metadata]
 name = python-troveclient
 summary = Client library for OpenStack DBaaS API
-description-file =
+description_file =
     README.rst
 author = OpenStack
-author-email = openstack-discuss@lists.openstack.org
-home-page = https://docs.openstack.org/python-troveclient/latest
-python-requires = >=3.6
+author_email = openstack-discuss@lists.openstack.org
+home_page = https://docs.openstack.org/python-troveclient/latest
+python_requires = >=3.6
 classifier =
     Environment :: OpenStack
     Intended Audience :: Information Technology
@@ -18,6 +18,7 @@ classifier =
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
     Programming Language :: Python :: 3.8
+    Programming Language :: Python :: 3.9
 
 [files]
 packages =

tox.ini

@@ -1,7 +1,7 @@
 # Python Trove Client
 
 [tox]
-envlist = py38,pep8
+envlist = py39,pep8
 minversion = 3.18.0
 skipsdist = True
 ignore_basepython_conflict = True