apply clippy fixes

[dishmaker]

pkcs12, x509-cert: clippy 0.1.100 (17fd5b8a37 2026-08-28)

warning: lint `clippy::from_iter_instead_of_collect` has been removed: lint has proved problematic
  |
  = note: requested on the command line with `-W clippy::from_iter_instead_of_collect`
  = note: `#[warn(renamed_and_removed_lints)]` on by default




warning: unneeded `return` statement with `?` operator
  --> x509-cert/src/ext/pkix/sct.rs:73:13
   |
73 |             return Err(tls_codec::Error::TrailingData)?;
   |             ^^^^^^^ help: remove it
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/main/index.html#needless_return_with_question_mark
   = note: `#[warn(clippy::needless_return_with_question_mark)]` on by default



warning: this `match` expression can be replaced with `?`
  --> pkcs12/src/safe_bag.rs:47:25
   |
47 |           let bag_value = match reader.tlv_bytes() {
   |  _________________________^
48 | |             Ok(v) => v.to_vec(),
49 | |             Err(e) => return Err(e),
50 | |         };
   | |_________^
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/main/index.html#question_mark
   = note: `#[warn(clippy::question_mark)]` on by default
help: try instead
   |
47 ~         let bag_value = {
48 +             let v = reader.tlv_bytes()?;
49 +             v.to_vec()
50 ~         };
   |