Clean up deprecated API in time module #63
Description
The inherent Time::try_from() method has been deprecated since briansmith/webpki#220 (and briansmith/webpki#139 before it). In addition, the TryFrom::Error type exposes ring as a public dependency (I believe this is the only item doing that). We should fix these issues in the next semver-breaking release (unfortunately we didn't do so for 0.100).