Merge #215: chore: fix cargo clippy warning

9390a63 chore: fix cargo clippy warning (xixishidibei)

Pull request description:

  Running cargo clippy reports the following error.

  ```shell
  warning: calling `as_bytes` after slicing a string
     --> src/primitives/decode.rs:138:30
      |
  138 |             data_part_ascii: rest[1..].as_bytes(), // Skip the separator.
      |                              ^^^^^^^^^^^^^^^^^^^^ help: try: `&rest.as_bytes()[1..]`
      |
      = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#sliced_string_as_bytes
      = note: `#[warn(clippy::sliced_string_as_bytes)]` on by default
  ```

  This commit resolves the issue.

ACKs for top commit:
  apoelstra:
    ACK 9390a63; successfully ran local tests
  clarkmoody:
    ACK 9390a63

Tree-SHA512: 28c237d5ea4587953aa4189604ce4fbf66491b5ba3115aba8011186b929c21795c69cfc76fcdf2ca4ccbbbef7e70103c46209b1d92f3161cb7145418468e7054

Author: apoelstra

src/primitives/decode.rs

@@ -135,7 +135,7 @@ impl<'s> UncheckedHrpstring<'s> {
 
         let ret = UncheckedHrpstring {
             hrp: Hrp::parse(hrp)?,
-            data_part_ascii: rest[1..].as_bytes(), // Skip the separator.
+            data_part_ascii: &rest.as_bytes()[1..], // Skip the separator.
             hrpstring_length: s.len(),
         };