Compilation error on OpenBSD

[jsbmg]

I'm getting the following error when compiling with Rust 1.55 on OpenBSD:

  Compiling dijo v0.2.7
error: #[ctor] is not supported on the current target
   --> /home/user/.cargo/registry/src/github.com-1ecc6299db9ec823/dijo-0.2.7/src/habit/traits.rs:104:1
    |
104 | generate_implementations!(Count, Bit, Float);
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: this error originates in the attribute macro `$crate::ctor` (in Nightly builds, run with -Z macro-backtrace for more info)

error: failed to compile `dijo v0.2.7`, intermediate artifacts can be found at `/tmp/cargo-installYknXva`

I'm not sure what the obstacles to building this are on OpenBSD but it would be great to have support for it and I would be happy to help in any way I can.