allowing more digits for SRA numbers

[rpolicastro]

The regex for SRA accession numbers checks for lengths 6 to 7. However, accession numbers go up to at least 8 digits now. This causes enaDataGet to fail for most new entries. I increased the upper limit to 10 to avoid this.

[puethe]

Not sure if this has unwanted side effects (I can't see any tests), but if you think it doesn't I would very much appreciate merging this in - it's a blocker for us at the moment.

[raskoleinonen]

SRA accessions can have 6 or more digits after the three letter prefix. For more information please see:
https://ena-docs.readthedocs.io/en/latest/submit/general-guide/accessions.html

e.g.
Runs | (E|D|S)RR[0-9]{6,} | ERR123456
Analyses | (E|D|S)RZ[0-9]{6,} | ERZ123456

[suranjayathilaka]

This has been fixed in a different PR. thanks!