fix: correct error message

Author: tri-adam

pkg/integrity/dsse.go

@@ -164,11 +164,11 @@ func (s *dsseSigner) Sign(ctx context.Context, data []byte) ([]byte, error) {
 return s.s.SignMessage(bytes.NewReader(data), opts...)
 }
 
-var errSignNotImplemented = errors.New("sign not implemented")
+var errVerifyNotImplemented = errors.New("verify not implemented")
 
 // Verify is not implemented, but required for the dsse.SignVerifier interface.
 func (s *dsseSigner) Verify(_ context.Context, _, _ []byte) error {
-return errSignNotImplemented
+return errVerifyNotImplemented
 }
 
 // Public returns the public key associated with s.