Misleading error message about key id instead of key bytes

[taladar]

In

https://docs.rs/cryptr/latest/src/cryptr/keys.rs.html#226

the error message from a few lines lower seems to be duplicated (error about the key id) even though the condition refers to the length of the key bytes which is the base64 decoded part after the / in ENC_KEYS.

[sebadob]

Oh you are right. Thanks! I will fix that.