define pluginManagement version for m-assembly-p

this closes #23

Author: hboutemy

pom.xml

@@ -347,6 +347,11 @@ limitations under the License.
     <pluginManagement>
       <plugins>
         <!-- set versions of common plugins for reproducibility, ordered alphabetically -->
+        <plugin>
+          <groupId>org.apache.maven.plugins</groupId>
+          <artifactId>maven-assembly-plugin</artifactId>
+          <version>3.3.0</version>
+        </plugin>
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-checkstyle-plugin</artifactId>