Allow alt text to be changed

[el]

https://github.com/napthedev/react-tuby/blob/d6dea37d8c90dfbec82a5590d133b8146effc234/src/components/Main.tsx#L396

If there is an issue with the poster, the poster title appears on screen, which is unchangeable right now. Please either allow us to change it or remove it.

Thanks

PS: as a workaround, following CSS rule can be used:

.tuby-poster
        {
            text-indent: -99999px;
        }