Add Crystal version from shard.yml and a filter option

[mjblack]

The one issue with listing all shards is that there are some that were developed for a really old version of Crystal. The shards developed with Crystal 0.24 might not be compatible with current release of Crystal or the inverse. It would be helpful to track and also being able to filter on shards based on Crystal version. It could also help filter out, or remove, shard listings for those that have been no longer maintained, and abandoned, based on last activity and Crystal version.

[Sija]

[...] It could also help filter out, or remove, shard listings for those that have been no longer maintained, and abandoned, based on last activity and Crystal version.

That's a common misconception re: Crystal shards, that lack of updates and old version stated in the shard.yml file means they are abandoned and/or won't work with new(er) versions of Crystal. In many cases lack of activity is dictated by the stability and feature-completeness and not by the abandonment.

One good example is the pool shard, which wasn't updated for the last 2 years and still works well, despite the lack of updates.