Set OpenVox Server 8.13.0 release date to 2026-05-04

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Signed-off-by: Michael Harp <mike@mikeharp.com>

Author: miharp

docs/_openvox-server_8x/release_notes.markdown

@@ -6,7 +6,7 @@ canonical: "/openvox-server/latest/release_notes.html"
 
 ## OpenVox Server 8.13.0
 
-Released TBD.
+Released 2026-05-04.
 
 This is an enhancement and bug-fix release of OpenVox Server.