Use the current version of XML Schema for Maven Assembly plugin

Author: garydgregory

src/assembly/src.xml

@@ -15,10 +15,9 @@ Licensed to the Apache Software Foundation (ASF) under one or more
  See the License for the specific language governing permissions and
  limitations under the License.
 -->
-<assembly
-  xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.0"
-  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-  xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.0 https://maven.apache.org/xsd/assembly-1.1.0.xsd">
+<assembly xmlns="http://maven.apache.org/ASSEMBLY/2.2.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/ASSEMBLY/2.2.0 https://maven.apache.org/xsd/assembly-2.2.0.xsd">
   <id>src</id>
   <formats>
     <format>tar.gz</format>