Adding Mateusz as an OWNER for Launcher tests

Bug: 187761685
Test: presubmit
Flag: N/A
Change-Id: I07a891fe766549208e4402726ee66998db22956d
diff --git a/tests/OWNERS b/tests/OWNERS
index 6b8643c..b5ee7d7 100644
--- a/tests/OWNERS
+++ b/tests/OWNERS
@@ -3,3 +3,4 @@
 sunnygoyal@google.com
 winsonc@google.com
 hyunyoungs@google.com
+mateuszc@google.com