Multiple fixes and enhancements

What's Changed

• Add VerifyAttestation contract and interface to npm package by @JamesSmartCell in #261
• Removed optional included pk in ticket by @jot2re in #263
• Fix ASN parse buffer conversion. by @micwallace in #257
• Fix typo in ticket schema by @micwallace in #264
• updated logging, error handling, added method to read key from PEM st… by @oleggrib in #265
• 246 constanttime by @jot2re in #248
• fix: 🐛 attestation request fix, test fix by @oleggrib in #272
• feat: 🎸 js implment for issue 246 by @oleggrib in #274
• Candidate for 0.4 by @jot2re in #298

Full Changelog: 0.3.18...0.4.0