.mailmap: add an alias for Plamena Manolova

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/1999>
diff --git a/.mailmap b/.mailmap
index 3f98fd3..2501494 100644
--- a/.mailmap
+++ b/.mailmap
@@ -485,6 +485,8 @@
 
 Pierre Willenbrock <pierre@pirsoft.de> Pierre Willenbrok <pierre@pirsoft.de>
 
+Plamena Manolova <plamena.manolova@intel.com> <plamena.n.manolova@gmail.com>
+
 Quentin Glidic <sardemff7+git@sardemff7.net> <sardemff7@sardemff7.net>
 
 RALOVICH, Kristóf <tade60@freemail.hu> <kristof.ralovich@gmail.com>