chore: remove unused field from ProcyonDecompiler.FileOutputWriter (#6324)

Author: commandini

spoon-decompiler/src/main/java/spoon/decompiler/ProcyonDecompiler.java

@@ -258,15 +258,12 @@ private Writer createWriter(TypeDefinition type, DecompilerSettings settings, St
 	}
 
 	final class FileOutputWriter extends OutputStreamWriter {
-		private final File file;
-
 		FileOutputWriter(final File file, final DecompilerSettings settings) throws IOException {
 			super(
 					new FileOutputStream(file),
 					settings.isUnicodeOutputEnabled() ? Charset.forName("UTF-8")
 							: Charset.defaultCharset()
 			);
-			this.file = file;
 		}
 	}