chore(motion_velocity_smoother): add maintainer (#6184)

Signed-off-by: Fumiya Watanabe <rej55.g@gmail.com>

Author: rej55

planning/motion_velocity_smoother/package.xml

@@ -8,6 +8,7 @@
   <maintainer email="fumiya.watanabe@tier4.jp">Fumiya Watanabe</maintainer>
   <maintainer email="takamasa.horibe@tier4.jp">Takamasa Horibe</maintainer>
   <maintainer email="makoto.kurihara@tier4.jp">Makoto Kurihara</maintainer>
+  <maintainer email="satoshi.ota@tier4.jp">Satoshi Ota</maintainer>
   <license>Apache License 2.0</license>
 
   <author email="takamasa.horibe@tier4.jp">Takamasa Horibe</author>