Security risk: Let's move to Lychee for broken links (and a note about other deps)

[lwasser]

Many of our dependencies are currently deprecated.
In #841 i notice we use BLC which hasn't been updated in 4 years. It would be good to consider moving to lychee which works well in CI and we could use and run on every build if we wish to.

For now I won't update it but i think we have a lot of dependency updates to do. Dated dependencies are a security risk for the project so we should prioritize it once we get things online.

[JimMadge]

I've used lychee before and have been quite happy with it.
It is fast (especially with caching), reliable and fairly easy to configure.

I suppose the downside is it is introducing a non-npm dependency, but I think that is acceptable because it is for developers/CI.

[lwasser]

Great! we definitely need a link checker. I'm really open to another tool if we don't want to use lychee. The issue is that our current npm based link checker is deprecated. Lychee is one I just know can be setup as a ci build easily.

@JimMadge are you open to working on this ? (and if you find something that you think is better that is ok too!!

Or are there other things that you'd prefer to work on? We are super close to getting the landing page of the website online #849 when merged has that down.

And we have crowdin acccess now too so we can figure out the translations. I'm open to who would like to work on what items. There is so much to do!!