Update setup.cfg
As reference:
@@ -5,11 +5,11 @@ max-line-length=99
[metadata]
license_file = LICENSE.txt
-provides-extra =
+provides_extra =
secure
socks
brotli
-requires-dist =
+requires_dist =
pyOpenSSL>=0.14; extra == 'secure'
cryptography>=1.3.4; extra == 'secure'
idna>=2.0.0; extra == 'secure'
