There is error in rust examples

There is a difference between rust example in Clarabel.rs repo and here. 
The solver needs to be _unwrapped_.
```rust
let mut solver = DefaultSolver::new(&P, &q, &A, &b, &cones, settings).unwrap();
```
instead of 
```rust
let mut solver = DefaultSolver::new(&P, &q, &A, &b, &cones, settings);
```
