Update the Super Good logo

As much as I enjoy the nostalgia of the logo I designed for us back in
the day, we now have a much nicer looking logo that was designed by
actual designers. This updates the README to use that.

README.md

@@ -47,7 +47,7 @@ At present, Nebulab is the main code contributor and director of Solidus, provid
 ### Ambassadors
 Support this project by becoming a Solidus Ambassador. Your logo will show up here with a link to your website. [Become an Ambassador](https://opencollective.com/solidus).
 
-[![Super Good Software](https://images.opencollective.com/proxy/images?src=https%3A%2F%2Fopencollective-production.s3-us-west-1.amazonaws.com%2F3bbb1440-727f-11e9-a366-37673cc38cee.png&height=100)](https://supergood.software/)
+[![Super Good Software](https://images.opencollective.com/supergoodsoft/f720462/logo/100.png)](https://supergood.software/)
 [![Karma Creative](https://images.opencollective.com/proxy/images?src=https%3A%2F%2Fopencollective-production.s3-us-west-1.amazonaws.com%2Fab94d2a0-7253-11e9-a366-37673cc38cee.png&height=100)](https://karmacreative.io/)
 [![ModdedEuros](https://images.opencollective.com/proxy/images?src=https%3A%2F%2Fimages.opencollective.com%2Fmodded-euros%2Ff1a80ae%2Flogo.png&height=100)](https://www.moddedeuros.com)