Upgrade bindgen to newest version

[ianks]

As part of 1.0, we need to upgrade bindgen to the latest release. We can use this opportunity to make some breaking configuration changes if needed as long as we can keep our msrv 1.61

see matsadler/magnus#42

cc: @matsadler When do you expect to release 0.6? I would like to get 1.0 out first if possible to avoid having to support sub-optimal binding configs. Happy to integrate whatever breaking changes rb-sys introduces into magnus, though.

[matsadler]

I'm hoping 0.6 will be done end of April/first week of May. Otherwise due to personal life commitments it'd probably end up middle of June.

I was actually going to ask to see if we could sync up a rb-sys 0.10/1.0 release with/before the Magnus 0.6 release. The other things I'd like to see would be changing VALUE to be an alias of usize (rather than platform dependent u32/u64), and updating syn to version 2 (I've already updated syn in Magnus' main branch. Things will work fine if rb-sys and Magnus use different versions, but it'd be nice if they were synced just to reduce the compilation time).

[ianks]

Sounds good to me. Let's sync up, I'll message you on the oxidize-rb Slack

also, #171 has a patch for syn v2