[MNT] SAX parallel numba without n_jobs parameter

[baraline]

Describe the issue

SAX uses numba parallel, albeit only for symbol inversion, but does not expose a n_jobs parameter to control the number of threads through numba set_num_threads.

Suggest a potential alternative/fix

No response

Additional context

No response

[hadifawaz1999]

my bad :) was my code, probably forgot to do that, good first issue ?

[baraline]

Should be easy yeah, a good addition would be to extend it using numba and parallelisation for the whole method, but that's one step ahead I guess.