Update log4j2 config and shadowJar task

Added 'packages' attribute to log4j2.xml Configuration for custom Log4j2 plugins. Removed mergeServiceFiles() from shadowJar task in build.gradle.kts, relying only on Log4j2PluginsCacheFileTransformer.

build.gradle.kts

@@ -61,7 +61,6 @@ repositories {
 }
 
 tasks.shadowJar {
-    mergeServiceFiles()
     transform(Log4j2PluginsCacheFileTransformer())
 }
 

src/main/resources/log4j2.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<Configuration status="WARN">
+<Configuration packages="pl.tkowalcz.tjahzi.log4j2" status="WARN">
   <Properties>
     <Property name="CONSOLE_LOG_PATTERN">%d{HH:mm:ss.SSS} %5p --- [%t] %c : %m%n</Property>
     <Property name="CONSOLE_LOG_CHARSET">UTF-8</Property>