refactor: It's not actually necessary for Alice to remember how the message was encrypted

src/decrypt.rs

@@ -19,7 +19,7 @@ pub fn try_decrypt<'a>(
     mail: &'a ParsedMail<'a>,
     private_keyring: &'a [SignedSecretKey],
     shared_secrets: &[String],
-) -> Result<Option<(::pgp::composed::Message<'static>, Option<usize>)>> {
+) -> Result<Option<::pgp::composed::Message<'static>>> {
     let Some(encrypted_data_part) = get_encrypted_mime(mail) else {
         return Ok(None);
     };