Re-bump to 0.8.0-pre again

semver 4.0.0 reverts to some behavior from 2.x but not all of it. In particular,
pre-release versions no longer match version ranges not declaring them
explicitly, e.g.:

    "jsdoc": "~3.3.0"

no longer matches "3.3.0-alpha9". This may break some builds so it's better to
bump the minor.