mixed_mode() missing 1 required positional argument: 'cores'

Trying to run in mixed mode.

I get the error below. Looking at the code, mixed_mode() is expecting an argument cores, byt cli.py is not giving it one. If it is that simple I can patch cli.py to include args.threads in the call to mixed_mode(). I'll give that a shot and send a pull request if it does. But let me know if I am missing something.

```
~/Downloads $ kc-align --reference arabidopsis_FLOE1.fasta --sequences strep_FLOE1_matches.fasta --mode mixed (base)
Traceback (most recent call last):
File "/opt/homebrew/Caskroom/miniconda/base/bin/kc-align", line 8, in
sys.exit(main())
File "/opt/homebrew/Caskroom/miniconda/base/lib/python3.9/site-packages/kcalign/cli.py", line 27, in main
return mixed_mode(args.reference, args.seqs, args.compress, args.table, args.keep, args.distance)
TypeError: mixed_mode() missing 1 required positional argument: 'cores'
```