v0.11.3

Tolerates every way the npm advisories endpoint fails, not just the slow one.

0.11.2 tolerated a hang past importmap`s read timeout by matching one error message. The endpoint then began answering fast with a 503 instead, which is the same condition in different words, so builds went red again.

bin/importmap-audit now tests for Importmap::Npm::HTTPError. That class is raised at every point where the registry fails to answer, and never by a real advisory, which prints a table and exits without raising.

No application code changed in this release.