Bug 1888488: update staging content signing root certificate to new cas_new root certificate r=jschanck

This is the cas_new root (https://bugzilla.mozilla.org/attachment.cgi?id=9390855) converted from PEM to DER with: `openssl x509 -in cas-new-root-2024-03-12.crt -inform PEM -outform DER` Differential Revision: https://phabricator.services.mozilla.com/D206040
2024-04-05 12:59:28 +00:00 · 2024-04-05 12:59:28 +00:00 · 1e4c36f8fd
--- a/security/manager/ssl/content-signature-stage.crt
+++ b/security/manager/ssl/content-signature-stage.crt