v4.1.0

• Adds support for go1.17 (#89).
• Adds RFC7519-compliant RegisteredClaims struct (#15). Use this instead of StandardClaims (deprecated but not removed).
• Adds generic crypto.Signer for ed25519.PublicKey (#95).
• Adds regular code scanning (#101).
• Corrects "exp" logic to conform to https://datatracker.ietf.org/doc/html/rfc7519#section-4.1.4 (#86).
• Adds additional parsing tests (#106).
• Changed error string (#97).
• Various Code fixes and cleanup (#53, #83, #102, #103).