Figure out if the collator needs a std feature

[hsivonen]

Issue (can be fixed after landing in experimental):

You either need an "std" feature, or you need to make the crate always no-std. I see that you have as a dependency

postcard = { version = "0.7", features = ["use-std"] }

The postcard/use-std feature should be toggled by the std feature on this crate. However, if you can disable that feature and everything still works, you might be okay.

Originally posted by @sffc in #1706 (comment)