mailmap: Add entry for Mickaël Salaün

My Microsoft address is no longer used.  Add a mailmap entry to reflect
that.

Cc: Günther Noack <gnoack@google.com>
Cc: James Morris <jamorris@linux.microsoft.com>
Reviewed-by: Paul Moore <paul@paul-moore.com>
Link: https://lore.kernel.org/r/20260207111136.577249-1-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>

Author: l0kod

.mailmap

@@ -557,6 +557,7 @@ Michel Dänzer <michel@tungstengraphics.com>
 Michel Lespinasse <michel@lespinasse.org>
 Michel Lespinasse <michel@lespinasse.org> <walken@google.com>
 Michel Lespinasse <michel@lespinasse.org> <walken@zoy.org>
+Mickaël Salaün <mic@digikod.net> <mic@linux.microsoft.com>
 Miguel Ojeda <ojeda@kernel.org> <miguel.ojeda.sandonis@gmail.com>
 Mike Rapoport <rppt@kernel.org> <mike@compulab.co.il>
 Mike Rapoport <rppt@kernel.org> <mike.rapoport@gmail.com>