Move Will Cassella to former editor

Publication to /TR currently fails because spec editors must be working group
participants, and Will is no longer around. This is per W3C Process, see:
https://www.w3.org/2023/Process-20231103/#publication

index.bs

@@ -8,8 +8,8 @@ Shortname: media-capabilities
 Level: None
 Group: mediawg
 Editor: Jean-Yves Avenard, w3cid 115886, Apple Inc. https://www.apple.com/
-Editor: Will Cassella, w3cid 139598, Google Inc. https://www.google.com/
 
+Former Editor: Will Cassella, w3cid 139598, Google Inc. https://www.google.com/
 Former Editor: Mounir Lamouri, w3cid 45389, Google Inc. https://www.google.com/
 Former Editor: Chris Cunningham, w3cid 114832, Google Inc. https://www.google.com/
 Former Editor: Vi Nguyen, w3cid 116349, Microsoft Corporation https://www.microsoft.com/