LenI is not correct

[russhousley]

RFC 8554 says: The parameter I is a 16-byte string that indicates which Merkle tree this LM-OTS is used with.

Thus, the LenI in the lms_params dict should be 16, not 64.

lms_params = {
# m, h, LenI
lms_sha256_m32_h5: (32, 5, 16),
lms_sha256_m32_h10: (32, 10, 16),
lms_sha256_m32_h15: (32, 15, 16),
lms_sha256_m32_h20: (32, 20, 16),
lms_sha256_m32_h25: (32, 25, 16)
}