Update package maintainers (#238)

This commit updates the package maintainers as the project's governance has changed a bit.

package.xml

@@ -18,11 +18,14 @@
   <author>Denis Stogl</author>
   <author>Andy Zelenak</author>
   <author>Marvin Grosse Besselmann</author>
-
-  <maintainer email="exner@fzi.de">Felix Exner</maintainer>
-  <maintainer email="schnell@fzi.de">Tristan Schnell</maintainer>
-  <maintainer email="lovro.ivanov@gmail.com">Lovro Ivanov</maintainer>
-  <maintainer email="denis@stoglrobotics.de">Denis Stogl</maintainer>
+  <author email="schnell@fzi.de">Tristan Schnell</author>
+  <author email="lovro.ivanov@gmail.com">Lovro Ivanov</author>
+  <author email="denis@stoglrobotics.de">Denis Stogl</author>
+  <author email="dipentima@fzi.de">Vincenzo Di Pentima</author>
+
+  <maintainer email="feex@universal-robots.com">Felix Exner</maintainer>
+  <maintainer email="rsk@universal-robots.com">Rune Søe-Knudsen</maintainer>
+  <maintainer email="ros@universal-robots.com">Universal Robots A/S</maintainer>
 
   <license file="LICENSE">BSD-3-Clause</license>
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