reduce memory for meryl count to avoid crash

[MartinPippel]

Avoid that meryl count crashes due to memory issues. It seems that meryl uses the complete buffer provided via memory=SIZE for the kmer counts, but meryl itself uses some memory too. When using meryl count within singularity containers and slurm, then usually slurm is killing meryl due to that overhead.

Solution, reduce the meryl memory kmer buffer task.memory by 10%. This is potentially a bit to much as usually the memory overhead was around 2-4Gb, but it solved all my issues on 3 three different compute clusters (Uppmax rackham, PDC dardel, and nac).

[mahesh-panchal]

This is fine, but need to get the tests working.