setup.cfg: Replace dashes with underscores (#1057)

Setuptools v54.1.0 introduces a warning that the use of dash-separated
options in 'setup.cfg' will not be supported in a future version [1].
Get ahead of the issue by replacing the dashes with underscores. Without
this, we see 'UserWarning' messages like the following on new enough
versions of setuptools:

  UserWarning: Usage of dash-separated 'build-requires' will not be
  supported in future versions. Please use the underscore name
  'build_requires' instead

  UserWarning: Usage of dash-separated 'doc-files' will not be
  supported in future versions. Please use the underscore name
  'doc_files' instead

[1] pypa/setuptools@a2e9ae4cb

Signed-off-by: Arthur Zamarin <[email protected]>

Author: arthurzam

setup.cfg

@@ -15,7 +15,7 @@ license_file = LICENSE
 # This is currently *not* actively tested.
 [bdist_rpm]
 release = 1
-build-requires = openssl-devel python-devel python-sphinx
+build_requires = openssl-devel python-devel python-sphinx
 group = Development/Libraries
 build_script = rpm/build_script
-doc-files = doc/_build/html
+doc_files = doc/_build/html