refactor: remove static modifier

Author: Umut Akbayin

jablib/src/main/java/org/jabref/logic/externalfiles/LinkedFileTransferHelper.java

@@ -19,7 +19,7 @@
 
 public class LinkedFileTransferHelper {
 
-  private static record FileCopyContext(
+  private record FileCopyContext(
     BibDatabaseContext sourceContext,
     BibDatabaseContext targetContext,
     FilePreferences filePreferences