Always return true when directory permission check

Author: sakama

src/main/java/org/embulk/output/sftp/provider/sftp/SftpFileObject.java

@@ -39,6 +39,6 @@ protected SftpFileObject(final AbstractFileName name, final SftpFileSystem fileS
     @Override
     protected boolean doIsWriteable() throws Exception
     {
-        return getPermissions(true).isWritable();
+        return true;
     }
 }