fix: fix a clippy warning (#300)

Fixes a clippy warning introduced in
#296. The CI pipeline didn't run
because changes in `rust-toolchain.toml` didn't trigger this workflow.
This PR also fixes this.

Author: fspreiss

.github/workflows/clippy.yml

@@ -15,6 +15,7 @@ on:
       - .github/workflows/provision-linux.sh
       - .github/workflows/provision-darwin.sh
       - .github/workflows/clippy.yml
+      - rust-toolchain.toml
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
   cancel-in-progress: true

backend/rs/ic_vetkeys/src/utils/mod.rs

@@ -639,7 +639,7 @@ impl DerivedKeyMaterial {
     fn derive_aes_gcm_key(&self, domain_sep: &str, version: u8) -> Vec<u8> {
         derive_symmetric_key(
             &self.key,
-            &format!("ic-vetkd-bls12-381-g2-aes-gcm-v{}-{}", version, domain_sep),
+            &format!("ic-vetkd-bls12-381-g2-aes-gcm-v{version}-{domain_sep}"),
             Self::GCM_KEY_SIZE,
         )
     }