Add myself to mailmap

Some tool used `Samuel "Sam" Tardieu` as a full name in some of the
commits imported along with clippy.

Author: samueltardieu

Diff for: .mailmap

@@ -494,6 +494,7 @@ Ryan Sullivant <rsulli55@gmail.com>
 Ryan Wiedemann <Ryan1729@gmail.com>
 S Pradeep Kumar <gohanpra@gmail.com>
 Sam Radhakrishnan <sk09idm@gmail.com>
+Samuel Tardieu <sam@rfc1149.net>
 Scott McMurray <scottmcm@users.noreply.github.com>
 Scott Olson <scott@solson.me> Scott Olson <scott@scott-olson.org>
 Sean Gillespie <sean.william.g@gmail.com> swgillespie <sean.william.g@gmail.com>