chore: added maintainer (autowarefoundation#7003)

added maintainer

Signed-off-by: Go Sakayori <gsakayori@gmail.com>

Author: go-sakayori

planning/behavior_path_planner_common/package.xml

@@ -25,6 +25,7 @@
   <maintainer email="fumiya.watanabe@tier4.jp">Fumiya Watanabe</maintainer>
   <maintainer email="takamasa.horibe@tier4.jp">Takamasa Horibe</maintainer>
   <maintainer email="zulfaqar.azmi@tier4.jp">Zulfaqar Azmi</maintainer>
+  <maintainer email="go.sakayori@tier4.jp">Go Sakayori</maintainer>
 
   <license>Apache License 2.0</license>