Bump francis to 0.0.18

[github-actions]

block/francis@v0.0.17...v0.0.18

Artifact: https://github.com/block/francis/releases/download/v0.0.18/francis-release.tar.gz
SHA256: 8e100129aaeedcfc76f01c5618603d4af6b9320a337440c8fd369ca73729498b

You can test your changes before merging this pull request with:

git -C $(brew --repo block/tap) fetch
git -C $(brew --repo block/tap) checkout origin/bump-francis-to-0.0.18
brew install block/tap/francis

When you're done, reset the tap with:

git -C $(brew --repo block/tap) checkout main