Updated to package.xml format 3.

Signed-off-by: Ralph Lange <[email protected]>

package.xml

@@ -1,16 +1,18 @@
 <?xml version="1.0"?>
-<package format="2">
+<?xml-model href="http://download.ros.org/schema/package_format3.xsd" schematypens="http://www.w3.org/2001/XMLSchema"?>
+<package format="3">
   <name>fmilibrary_vendor</name>
   <version>1.0.1</version>
   <description>Wrapper (aka vendor package) around the FMILibrary by Modelon AB (JModelica.org)</description>
 
   <maintainer email="[email protected]">Christian Bertsch</maintainer>
-  <author email="[email protected]">Ralph Lange</author>
 
   <license>BSD-3-Clause</license><!-- The license of FMILibrary. -->
 
   <url type="website">https://jmodelica.org/</url>
 
+  <author email="[email protected]">Ralph Lange</author>
+
   <buildtool_depend>ament_cmake</buildtool_depend>
   <build_depend>git</build_depend>
   <export>