Bump html-proofer from 3.18.8 to 3.19.1

Bumps html-proofer from 3.18.8 to 3.19.1.

Release notes

Sourced from html-proofer's releases.

v3.19.0

• Support hydra config on CLI #632

Commits

• 249d506 💎 bump to 3.19.1
• 3b2e7cc Merge pull request #637 from gjtorikian/double-ua
• ef3d8bd Does not work in CI
• a7eb1a6 Address wild double UA bug
• 3e79177 💎 bump to 3.19.0
• f5cc410 Merge pull request #632 from patcon/patch-1
• b274614 Fixed spec tests.
• bdf2484 Ensure config keys are symbolized when parsing JSON from CLI.
• 1707bd7 Added --hydra-config flag to override concurrency from CLI.
• 101059f let push through
• See full diff in compare view