allow use of .gz when specifying fast and gtf

[ChristopherMancuso]

Description of feature

I was trying to run the scrnaseq pipeline specifying a fasta and gtf file. I downloaded from ensembl but they were gunzipped.

I searched Slack and found the same problem I was having and this answer that seems to have worked for me too
https://nfcore.slack.com/archives/CHN5BV5DW/p1706103433405269

I was wondering if it would be possible to allow the use of .gz files like this? I have used the rnaseq pipeline and it allows for the use of gunzipped files. Thanks for this amazing resource!

[grst]

Will be fixed as part of #276.

[nick-youngblut]

Just for the gtf of refdata-gex-GRCh38-2024-A, the file size balloons from 61 Mb to 1.7 Gb when gunzip'd. It will be great to be able to use the gzip'd versions of the fasta and gtf files.

[pinin4fjords]

Still seems to be an issue in latest release

[grst]

#276 has not been merged yet, this will be part of 2.7