Go 1.25 disabled SHA-1 signature algorithms in TLS 1.2 according to RFC 9155.
The default can be reverted using the `tlssha1=1` setting.

Go 1.25 switched to SHA-256 to fill in missing SubjectKeyId in
crypto/x509.CreateCertificate. The setting `x509sha256skid=0` reverts to SHA-1.

Go 1.25 corrected the semantics of contention reports for runtime-internal locks,

pkg crypto/x509, type Certificate struct, SignatureAlgorithm SignatureAlgorithm
pkg crypto/x509, type Certificate struct, Subject pkix.Name
pkg crypto/x509, type Certificate struct, SubjectKeyId []uint8
pkg crypto/x509, type Certificate struct, UnknownExtKeyUsage []asn1.ObjectIdentifier
pkg crypto/x509, type Certificate struct, Version int
pkg crypto/x509, type CertificateInvalidError struct