Make two Dimitis into one

Before:

    ❯ git shortlog -sn 598a6c0..
         ...
         3  Ben Dichter
         2  Dimitri Papadopoulos Orfanos
         2  Teon L Brooks
         1  Ariel Rokem
         1  Dimitri Papadopoulos

After:

    ❯ git shortlog -sn 598a6c0.. | grep -v bot
         ...
         3	Ben Dichter
         3	Dimitri Papadopoulos Orfanos
         2	Teon L Brooks

.mailmap

@@ -64,3 +64,5 @@ Patrick Park <[email protected]>
 Ezequiel Mikulan <[email protected]>
 
 Guillaume Flandin <[email protected]>
+
+Dimitri Papadopoulos Orfanos <[email protected]>