fix: correct Joe's @-mention in invited_tsc

Refs: nodejs/TSC#1643 (comment)

Author: richardlau

templates/invited_tsc

@@ -24,4 +24,4 @@
 * Geoffrey Booth @GeoffreyBooth (regular member)
 * Shelley Vohr @codebytere (regular member)
 * Rich Trott @Trott (regular member)
-* Joe Sepi @sepi@joesepi.com (Guest - Node.js CPC rep)
+* Joe Sepi @joesepi (Guest - Node.js CPC rep)