Fix clippy issue on Rust 1.75

With the recent release of Rust 1.75 there were some new clippy rules
enabled. There was one minor usage issue highlighted in the new release.
While we pin the rust version in CI when building and running clippy
locally with the latest version this would trigger a failure. This
commit fixes the one issue highlighted by clippy on Rust 1.75 which
replaces `Vec<T>.get(0)` with `Vec<T>.first()`.

crates/accelerate/src/results/marginalization.rs

@@ -132,7 +132,7 @@ pub fn marginal_memory(
     parallel_threshold: usize,
 ) -> PyResult<PyObject> {
     let run_in_parallel = getenv_use_multiple_threads();
-    let first_elem = memory.get(0);
+    let first_elem = memory.first();
     if first_elem.is_none() {
         let res: Vec<String> = Vec::new();
         return Ok(res.to_object(py));