Fix new warnings added in recent Rust versions.

Author: cgranade

src/Simulation/qdk_sim_rs/benches/c_api_benchmark.rs

@@ -46,7 +46,8 @@ fn with_test_suite<T: criterion::measurement::Measurement>(
 fn ideal(c: &mut Criterion) {
     let mut sim_id: usize = 0;
     unsafe {
-        let _err = c_api::init(3, CString::new("mixed").unwrap().as_ptr(), &mut sim_id);
+        let repr = CString::new("mixed").unwrap();
+        let _err = c_api::init(3, repr.as_ptr(), &mut sim_id);
     }
     let mut group = c.benchmark_group("ideal");
     with_test_suite(sim_id, &mut group);
@@ -57,7 +58,8 @@ fn ideal(c: &mut Criterion) {
 fn noisy(c: &mut Criterion) {
     let mut sim_id: usize = 0;
     unsafe {
-        let _err = c_api::init(3, CString::new("mixed").unwrap().as_ptr(), &mut sim_id);
+        let repr = CString::new("mixed").unwrap();
+        let _err = c_api::init(3, repr.as_ptr(), &mut sim_id);
     }
     // NB: The C API is not in general safe.
     unsafe {

src/Simulation/qdk_sim_rs/tests/chp_simulation_tests.rs

@@ -1,7 +1,7 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
-use qdk_sim::{Pauli, Process, State, Tableau};
+use qdk_sim::{Pauli, Process, State};
 
 #[test]
 fn pauli_channel_applies_correctly() -> Result<(), String> {