WEB: Update sponsors in website
Still waiting for the logos of the new sponsors, and final confirmation that we want to replace Ursa Labs by Voltron, but opening early in case there is feedback.
> Can probably add Nvidia, will confirm and find what image to use

I forgot about Nvidia, sorry. Thanks for the heads up, added it now. This should be ready now. This is how the home page look with the new sponsors:

![Screenshot at 2022-07-22 12-08-47](https://user-images.githubusercontent.com/10058240/180368415-bc3d1f45-ee97-4614-9b9c-732f896c6750.png)

@mroeschke I found the nvidia logo online, I think it should be fine.

I watched @jreback recent talk, and I'm wondering whether we should also add USC (who sponsored @jbrockmendel to work on the non-nanosecond stuff via Quansight), and NASA (I don't know much about that grant). No strong opinion, but if we add them let's do it in a follow up PR, since getting the logos takes a while and this is ready now.  > @mroeschke I found the nvidia logo online, I think it should be fine.
 
Thanks. I am still inquiring within my company to get approval to use the logo, but if you'd like to merge this and add Nvidia's logo (and the others) in a followup I would be fine with that I'll split this in two and have nvidia in a separate PR, so we can get the rest merged, and nvidia is ready for whenever the decision is made. Thanks for letting me know. @datapythonista I just got approval now that the Nvidia logo usage is good!
