removing the entry for a removed sponsor image

image (logo of "c") is removed.
https://github.com/conversejs/converse.js/commit/c6bc5e14383900b5deab90792bb2684518ffd541

docs/source/_templates/sponsors.html

@@ -14,10 +14,6 @@
             <img style="width: 9em" src="/logo/blokt.png" alt="Blokt Crypto & Privacy">
         </a>
     </li>
-    <li><a href="https://originalenergie.de/?utm_source=conversejs" target="_blank" rel="noopener">
-            <img style="width: 9em" src="/logo/originalenergie-black.png" alt="Original Energie">
-        </a>
-    </li>
     <li><a href="https://primesound.org/?utm_source=conversejs" target="_blank" rel="noopener">
             <img style="width: 9em" src="/media/logos/primesound.png" alt="Prime Sound">
         </a>