Repos.java:377-381: Make 'with' method immutable....

The puzzle `1660-338c6d7a` from #1660 has to be resolved:

https://github.com/jcabi/jcabi-github/blob/090fbe1618c811e5bcbc4b4a8105f3d8b6f7daab/src/main/java/com/jcabi/github/Repos.java#L377-L381

The puzzle was created by volodya-lombrozo on 04-Aug-23.

Estimate: 30 minutes, role: DEV.

If you have any technical questions, don't ask me, submit new tickets instead. The task will be \"done\" when the problem is fixed and the text of the puzzle is _removed_ from the source code. Here is more about [PDD](http://www.yegor256.com/2009/03/04/pdd.html) and [about me](http://www.yegor256.com/2017/04/05/pdd-in-action.html).