Bump Sphinx from 1.7.3 to 1.7.4
Bump Sphinx from 1.7.3 to 1.7.4

Bumps [Sphinx](http://sphinx-doc.org/) from 1.7.3 to 1.7.4.

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
gpodder/mygpo-auth,gpodder/mygpo-auth