chore: update sponsorship graphic

[chailandau]

Summary

Speakeasy has a new brand! We are updating our sponsorship logo graphic :]

Checklist

• I understand that this PR may be closed in case there was no previous discussion. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.

[chailandau]

@tomchristie are you able to merge this in? I dont seem to have the ability

[chailandau]

@tomchristie @zanieb the graphic doesn't seem to be updated on the live site, is there anything else I need to do?