Fix username

Co-authored-by: Mark Rousskov <[email protected]>

Author: joshtriplett

teams/lang-advisors.toml

@@ -9,7 +9,7 @@ members = [
     "jackh726",
     "JakobDegen",
     "RalfJung",
-    "simulacrum",
+    "Mark-Simulacrum",
     "wesleywiser",
 ]