cob: move unwrap_used pragma — heartwood

Clippy does not recognise this allow pragma to be used at the unwrap call site. Instead, if it’s moved up to the match case it will be recognised.

 impl From<CommitTrailer> for Trailer<'_> {
     fn from(t: CommitTrailer) -> Self {
         match t {
             #[allow(clippy::unwrap_used)]
             CommitTrailer::Related(oid) => {
                 Trailer {
                     // SAFETY: "Rad-Related" is a valid `Token`.
                     #[allow(clippy::unwrap_used)]
                     token: Token::try_from("Rad-Related").unwrap(),
                     value: oid.to_string().into(),
                 }
             }
             #[allow(clippy::unwrap_used)]
             CommitTrailer::Resource(oid) => {
                 Trailer {
                     // SAFETY: "Rad-Resource" is a valid `Token`.
                     #[allow(clippy::unwrap_used)]
                     token: Token::try_from("Rad-Resource").unwrap(),
                     value: oid.to_string().into(),
                 }