slurm 20 updates

[JRWallace]

oscar is now running slurm 20 rather than slurm 17, so bioflows returns this error:

2021-01-16 10:06:23,030: radical.saga.cpi    : MainProcess                     : MainThread     : ERROR   : NoSuccess: Couldn't get job id from submitted job! sbatch output:
sbatch: unrecognized option '--workdir'
Try "sbatch --help" for more information

Update bioflows so that --workdir is replaced with --chdir (or -D)

see slurm docs for more info:
https://slurm.schedmd.com/archive/slurm-17.02.0/sbatch.html
https://slurm.schedmd.com/sbatch.html