Non-deterministic order of migrations makes reproducable builds impossible

[stevenroose]

I'm trying to make a reproducable build of a binary that uses refinery. It seems that the order the migrations are encoded by refinery::embed_migrations is system-dependent (filesystem read order, which is salted on ext4).

This means that it's impossible to make the build reproducible.

I'm currently writing the module manually using a build.rs script, but it would be nice if the macro would fix the ordering.

[silverpill]

I fixed it in #439
But it was closed by bot 🤷