refactor(logger): remove accidential class field declaration

src/main/java/de/hftstuttgart/unifiedticketing/core/Logging.java

@@ -16,7 +16,7 @@ public class Logging
         mainLogger.setUseParentHandlers(false);
         handler = new ConsoleHandler();
         handler.setFormatter(new SimpleFormatter() {
-            private static final String format = "[%1$tFT%1$tT%1$tz] [%2$-7s] [%3$s.%4$s] %5$s%n";
+            final String format = "[%1$tFT%1$tT%1$tz] [%2$-7s] [%3$s.%4$s] %5$s%n";
 
             @Override
             public synchronized String format(LogRecord lr) {