Request: support longer OTP secrets, up to 64 bytes

[szszszsz]

PSN (https://my.playstation.com) sends its TOTP secrets as long as 64 bytes, which is bigger than currently supported 40 bytes.
Algorithm used is probably HMAC-SHA512, which needs such input.

Example:

• 7SA3NSIABTSZQP7VBPF6CAA5OAHEKVIZ27PRVN6VU5FWE3FFWXTNQZCGMH62JLFJR6SHCBCYE3MMKNNZMQ5THZYPZAB5HH34XKXLKAA (original, misses padding A at the end to properly parse)