v0.12.0

• add SignedJwt.unprotect() method to remove a JWT signature. by @guillp in #26
• add Jwk.from_pkcs12() method to load a private key from a PKCS12 by @guillp in #27
• allow loading public keys as Jwk from X509 certificates, either PEM or DER encoded, or from cryptography Certificate instances directly, optionally with a x5t or x5t#S256 parameter. by @guillp in #29
• handle max_size parameter on every token constructor by @guillp in #32
• misc packaging updates