sslutil: print SHA-256 fingerprint by default The world is starting to move on from SHA-1. A few commits ago, we gained the ability to define certificate fingerprints using SHA-256 and SHA-512. Let's start printing the SHA-256 fingerprint instead of the SHA-1 fingerprint to encourage people to pin with a more secure hashing algorithm. There is still a bit of work to be done around the fingerprint messaging. This will be addressed in subsequent commits.