Bump shellcheck to v0.8.0 (#18014)
Bump shellcheck to v0.8.0 (#18014)

Bump shellcheck to the more recent version, pulling from GitHub instead of apt.

See https://github.com/koalaman/shellcheck/tree/v0.8.0#installing (pre-compiled
binaries).
gravitational/teleport,gravitational/teleport,gravitational/teleport,gravitational/teleport,gravitational/teleport,gravitational/teleport