Remove animal sniffer (not supported with newer JDKs anymore)

Replace with maven.compiler.release for JDKs > 8
diff --git a/maven_plugin_config-master/pom.xml b/maven_plugin_config-master/pom.xml
index 5c79e4f..218df89 100644
--- a/maven_plugin_config-master/pom.xml
+++ b/maven_plugin_config-master/pom.xml
@@ -25,7 +25,7 @@
 
   <properties>
     <jdk.min.version>1.8</jdk.min.version>
-    <jdk.source.version>1.8</jdk.source.version>
+    <jdk.source.version>8</jdk.source.version>
     <maven.compiler.source>${jdk.source.version}</maven.compiler.source>
     <maven.compiler.target>${jdk.source.version}</maven.compiler.target>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>