Add tomnom@ to OpenGL OWNERS and remove vantablack.

OpenGL and vulkan share the same owners list. Clean up both of them to remove devs who no longer work in these areas.

Bug: 355048056
Change-Id: I1e3e53aa3908c6e13788a294d5b56f624410d266
Test: n/a

Author: tomnomgoogleuk

opengl/OWNERS

@@ -2,5 +2,4 @@ chrisforbes@google.com
 cnorthrop@google.com
 ianelliott@google.com
 jessehall@google.com
-lpy@google.com
-vantablack@google.com
+tomnom@google.com