chore(deps): bump github.com/pointfreeco/swift-snapshot-testing (#764)

Bumps [github.com/pointfreeco/swift-snapshot-testing](https://github.com/pointfreeco/swift-snapshot-testing) from 1.18.4 to 1.18.6.
- [Release notes](https://github.com/pointfreeco/swift-snapshot-testing/releases)
- [Commits](pointfreeco/swift-snapshot-testing@1.18.4...1.18.6)

---
updated-dependencies:
- dependency-name: github.com/pointfreeco/swift-snapshot-testing
  dependency-version: 1.18.6
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Author: dependabot[bot]