--paths doesn't find ONT reads unless --nano is supplied.

[brianwalenz]

verkko \
  --paths some.gaf \
  --assembly some-assembly \
  -d some-output \
  --hifi hifi/*fastq.gz

will fail to include ONT reads even if they exist in some-assembly because 7-buildPackages.sm sets the ont subset file to emptyfile if there are not ONT reads supplied to verkko:

checkpoint buildPackages:
    input:
        hifi       = HIFI_READS,
        layout     = {rules.layoutContigs.output.layout},
        ont_subset = {rules.extractONT.output.ont_subset} if config['withONT'] == "True" else {rules.emptyfile.output}