git2::IndexTime is not ready for year 2038

Trying to construct a [`git2::IndexTime`](https://docs.rs/git2/latest/git2/struct.IndexTime.html), I noticed that the signature of `new` is not year 2038 compatible. ```rust pub fn new(seconds: i32, nanoseconds: u32) -> IndexTime ``` The function takes a signed 32-bit integer, which will overlow somewhere in 2038. More information at https://theyear2038problem.com/ I see that the issue seems to be fixed in `master` but not yet published. I'll close this issue if the new version gets published.