Memory leak in src/condense_solver.c

A memory leak was observed in `src/condense_solver.c`.

It looks like the linear solver `LS` is not freed before the function exits. I suggest adding the following line:

```c
SUNLinSolFree(LS);
```

after

```c
CVodeFree(&cvode_mem);
```

around line 177 in `condense_solver.c`.