Use of deprecated Jax APIs/behavior

[pfrommerd]

Trajax uses deprecated Jax APIs/behavior which result in warnings being emitted in two locations.

1. The first instance is at
   

   trajax/trajax/optimizers.py

   Line 755 in a14d248

    @partial(jit, static_argnums=(0, 1, 9)) 

   
   where argnum 9 is specified although the function only has 8 arguments. This results in the warning:

jax/_src/api_util.py:165: SyntaxWarning: Jitted function has static_argnums=(0, 1, 9), but only accepts 8 positional arguments. 
This warning will be replaced by an error after 2022-08-20 at the earliest.

2. The second warning is at
   

   trajax/trajax/tvlqr.py

   Line 98 in a14d248

    K = -sp.linalg.solve(G_, H, sym_pos=True) 

   
   which raises the following warning

trajax/tvlqr.py:98: FutureWarning: The sym_pos argument to solve() is deprecated and will be removed in a future JAX release. Use assume_a='pos' instead.

[Jannik Grothusen]

The second warning should be fixed in #10.