Bump gds-sso to 9.3.0

This is to fix an issue with transfer ot bearer tokens.  See
https://github.com/alphagov/signonotron2/pull/245 for details.
Remove gemfury from sources.

We don't load any gems from there any more.
Merge pull request #33 from alphagov/bump_gds-sso

Bump gds-sso to 9.3.0