setup.cfg: Replace dashes by underscores

Since setuptools v54.1.0[1], the parmeters with dash have been
deprecated in favor of the new parameters with underscore.

This change updates the parameters accordingly to avoid the warnings
like the example below.

  UserWarning: Usage of dash-separated 'description-file' will not be
  supported in future versions. Please use the underscore name
  'description_file' instead

[1] https://github.com/pypa/setuptools/commit/a2e9ae4cb

Change-Id: I5f702cde6d5bc3f0019e556e881b1c49b600f80b
diff --git a/setup.cfg b/setup.cfg
index d7d3196..954fe98 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,12 +1,12 @@
 [metadata]
 name = octavia-tempest-plugin
 summary = Tempest plugin for Octavia
-description-file =
+description_file =
     README.rst
 author = OpenStack
-author-email = openstack-discuss@lists.openstack.org
-home-page = https://docs.openstack.org/octavia-tempest-plugin/latest/
-python-requires = >=3.6
+author_email = openstack-discuss@lists.openstack.org
+home_page = https://docs.openstack.org/octavia-tempest-plugin/latest/
+python_requires = >=3.6
 classifier =
     Environment :: OpenStack
     Intended Audience :: Information Technology
@@ -22,7 +22,7 @@
     Programming Language :: Python :: 3.8
 
 [global]
-setup-hooks =
+setup_hooks =
     pbr.hooks.setup_hook
 
 [files]