Upgrade to Maven Wrapper 3.8.4.

See #313

Author: mp911de

.mvn/wrapper/maven-wrapper.properties

@@ -1,2 +1,2 @@
-#Mon Oct 11 14:30:25 CEST 2021
-distributionUrl=https\://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.8.3/apache-maven-3.8.3-bin.zip
+#Tue Feb 22 13:56:03 CET 2022
+distributionUrl=https\://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.8.4/apache-maven-3.8.4-bin.zip