`PyErr` conversion for `TryFromFloatSecsError` (and other missing stdlib errors?)

I noticed we don't have a conversion to `PyErr` from [`TryFromFloatSecsError`](https://doc.rust-lang.org/stable/core/time/struct.TryFromFloatSecsError.html). It's probably trivial to add one to `src/err/impls.rs`. I wonder if there are any (relatively) new standard library errors we currently lack, it might be interesting to audit.