[website] Remove Spice logo from sponsor section.

Summary:
The project requested to be removed from the page.
Thank you to the Spice Token project for your support.

Test Plan:
Built and ran it locally
Confirmed with Spice people that they want their logo removed.

Reviewers: johnkuney, jasonbcox, deadalnix, #bitcoin_abc, josephroyking

Reviewed By: #bitcoin_abc, josephroyking

Subscribers: josephroyking

Differential Revision: https://reviews.bitcoinabc.org/D8574