Fix broken unit test, migrate to Go 1.17 for CI

Changelog for v0.6.6:

Commits
d791db5 Convert to Go 1.17 by @alexellis
fa46e5a Fix broken unit test in 404 use-case by @alexellis
670e9c7 Inline two err check statements by @alexellis

Changes: v0.6.5...v0.6.6

Generated by Derek