meta: add mailmap entry for aditi-1400

PR-URL: #59316
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: Aditi-1400

.mailmap

@@ -6,6 +6,7 @@ Abdirahim Musse <abdirahim.musse@ibm.com> <33973272+abmusse@users.noreply.github
 Abe Fettig <abefettig@gmail.com> <abe@fettig.net>
 Abhimanyu Vashisht <abhimanyuvashisht.av@gmail.com>
 Adam Langley <agl@imperialviolet.org> <agl@google.com>
+Aditi Singh <aditisingh1400@gmail.com>
 Akhil Marsonya <akhil.marsonya27@gmail.com>
 Akhil Marsonya <akhil.marsonya27@gmail.com> <16393876+marsonya@users.noreply.github.com>
 Akito Ito <akito0107@gmail.com> <akito_ito@r.recruit.co.jp>