fix uukanshu possible failure on synopsis

[camp00000]

Found on #2270

This source suffers from rate-limiting after a certain point (only X amount of requests per hour/day allowed, etc) with cloudflare or similar blocking any further requests after a certain point for some time -> is there any way to force proxies or make a popup appear on all log levels for the user to let them know of this limitation that can/should be bypass with proxies if it occurs?

[dipu-bd]

There is configuration for ratelimiting here: self.init_executor(ratelimit=0.5)

Check https://github.com/dipu-bd/lightnovel-crawler/blob/dev/lncrawl/core/taskman.py#L56

[dipu-bd]

I think making a message appearing to the user everytime they try to download a novel can become annyoing to some. However, we can add a section in the REAMDE to describe usage of proxies and ratelimiting.

[camp00000]

Thanks for the info on the rate_limiting, I realized I may have confused this source's rate-limiting with that of another since I can't find the comments/issues I had in mind right now, but regardless I'll keep this in mind going forward and maybe will create a PR updating the README at some point in the future.

Update: I confused the rate-limiting of this source with that of 69xinshu, see #2269 for more details