`--maxMemory` doesn't work

Hi,

I tried the following command:

```bash
nextflow run IGDRion/ANNEXA \
    -profile test,singularity \
    --maxMemory 12 --maxCpu 4
```

But I'm getting

```bash
ERROR ~ Error executing process > 'INDEX_BAM (popsi_19.bam)'

Caused by:
  Process requirement exceeds available memory -- req: 16 GB; avail: 15.6 GB
```