Remove the std default feature

[notgull]

Added in 272bb11 for reasons that are unclear to me. It serves no purpose aside from disabling the API of the entire crate, so it's best to remove it.

[fogti]

what about the CI change in the original commit? (I checked now, it's no longer present)

[notgull]

what about the CI change in the original commit? (I checked now, it's no longer present)

Looks like it was removed in dec94cb when taiki-e was cleaning up the CI configuration

[taiki-e]

This was necessary to add no-std support without requiring a breaking change. (crossbeam-rs/crossbeam#508 (comment) has a more detailed explanation of this.)

However, given that we have decided not to do #87, that may no longer be necessary.

what about the CI change in the original commit? (I checked now, it's no longer present)

Looks like it was removed in dec94cb when taiki-e was cleaning up the CI configuration

That check was not just removed, but replaced with a more robust cargo hack build --feature-powerset --no-dev-deps.