sdk/rust: fix clippy error

sdk/rust/core/src/serde_array.rs

@@ -23,7 +23,7 @@ impl<'de, const N: usize> Visitor<'de> for ArrayVisitor<N> {
     type Value = [u8; N];
 
     fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-        write!(formatter, "an array of length {}", N)
+        write!(formatter, "an array of length {N}")
     }
 
     fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>

sdk/rust/serde_wormhole/src/lib.rs

@@ -209,7 +209,7 @@ mod tests {
             type Value = [u8; N];
 
             fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-                write!(formatter, "an array of length {}", N)
+                write!(formatter, "an array of length {N}")
             }
 
             fn visit_seq<A>(self, mut seq: A) -> Result<Self::Value, A::Error>