Update BACKERS.md

[skip ci]

BACKERS.md

@@ -10,12 +10,12 @@ This is a list of all the people who are contributing financially to Panda3D.  I
 
 ## Bronze Sponsors
 
-![Bronze Sponsors](https://opencollective.com/panda3d/tiers/bronze-sponsor.svg?avatarHeight=48&width=600)
+[<img src="https://www.panda3d.org/wp-content/uploads/2021/02/changecrab_logo.png" alt="ChangeCrab" height="48">](https://changecrab.com/) ![Bronze Sponsors](https://opencollective.com/panda3d/tiers/bronze-sponsor.svg?avatarHeight=48&width=600)
 
 * [Mitchell Stokes](https://opencollective.com/mitchell-stokes)
 * [Daniel Stokes](https://opencollective.com/daniel-stokes)
 * [David Rose](https://opencollective.com/david-rose)
-* [Robert Clarke](https://opencollective.com/robert-clarke)
+* [ChangeCrab](https://changecrab.com)
 
 ## Benefactors