$ cp -r examples/ch04/budget-vs-actual-1 /tmp/budget-vs-actual-1
$ perl -pi -e 'print "metadata:\n  pack-version: 0.1\n" if $. == 4' /tmp/budget-vs-actual-1/SKILL.md
$ grep -A1 '^metadata:' /tmp/budget-vs-actual-1/SKILL.md
metadata:
  pack-version: 0.1
$ python3 tools/validate_pack.py --auto /tmp/budget-vs-actual-1
/tmp/budget-vs-actual-1: FAIL (split, 0/20 files, 0 bytes below the root)
  error: SKILL.md: spec 2.6: metadata must map strings to strings (quote numbers)
