Add Adam Zieliński to the mailmap file.

Adds Adam Zieliński's display name to the `.mailmap` file.

Developed in https://github.com/wordpress/wordpress-develop/7204
Discussed in https://core.trac.wordpress.org/ticket/61864

Follow-up to [58899].

Props dmsnell, zieladam.
See #61864.


git-svn-id: https://develop.svn.wordpress.org/trunk@58941 602fd350-edb4-49c9-b593-d223f7449a82

.mailmap

@@ -9,6 +9,8 @@
 Aaron D. Campbell <aaroncampbell@git.wordpress.org> <aaroncampbell@602fd350-edb4-49c9-b593-d223f7449a82>
 Aaron Jorbin <jorbin@git.wordpress.org> <jorbin@602fd350-edb4-49c9-b593-d223f7449a82>
 Adam Silverstein <adamsilverstein@git.wordpress.org> <adamsilverstein@602fd350-edb4-49c9-b593-d223f7449a82>
+Adam Zieliński <zieladam@git.wordpress.org> <zieladam@602fd350-edb4-49c9-b593-d223f7449a82>
+Adam Zieliński <zieladam@git.wordpress.org>
 Alex King <alexkingorg@git.wordpress.org> <alexkingorg@602fd350-edb4-49c9-b593-d223f7449a82>
 Alex Shiels <tellyworth@git.wordpress.org> <tellyworth@602fd350-edb4-49c9-b593-d223f7449a82>
 André <oandregal@git.wordpress.org>