Update mailmap for me

Author: fee1-dead

.mailmap

@@ -72,6 +72,7 @@ Daniel Ramos <dan@daramos.com>
 David Klein <david.klein@baesystemsdetica.com>
 David Manescu <david.manescu@gmail.com> <dman2626@uni.sydney.edu.au>
 David Ross <daboross@daboross.net>
+Deadbeef <ent3rm4n@gmail.com> <fee1-dead-beef@protonmail.com>
 Derek Chiang <derekchiang93@gmail.com> Derek Chiang (Enchi Jiang) <derekchiang93@gmail.com>
 Diggory Hardy <diggory.hardy@gmail.com> Diggory Hardy <github@dhardy.name>
 Donough Liu <ldm2993593805@163.com> <donoughliu@gmail.com>