update m-shade-p for Reproducible Builds (#17)

diff --git a/pom.xml b/pom.xml
index 500d639..d6f31c8 100644
--- a/pom.xml
+++ b/pom.xml
@@ -60,7 +60,7 @@
            <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-shade-plugin</artifactId>
-                <version>3.2.1</version>
+                <version>3.2.4</version>
                 <executions>
                     <execution>
                         <phase>package</phase>