Nextflow lint cleanup sratools/prefetch

[LouisLeNezet]

PR checklist

We need to fix the depreacted shell environment.
To do so multiple solution exist.
Here is a proposition.

• We can keep the template but then we need to escape all $ in the script and echo all unused variable (cleaner)
• We can call with bash the script and pass the variable either by positional argument or as environment variable.

I've updated the module to use topic and updated it to 3.2.1 as mentioned in phac-nml/fetchdatairidanext#30