Upgrade: Bump c8 from 7.14.0 to 8.0.0 (#111)

Bumps [c8](https://github.com/bcoe/c8) from 7.14.0 to 8.0.0.
- [Release notes](https://github.com/bcoe/c8/releases)
- [Changelog](https://github.com/bcoe/c8/blob/main/CHANGELOG.md)
- [Commits](bcoe/c8@v7.14.0...v8.0.0)

---
updated-dependencies:
- dependency-name: c8
  dependency-type: direct:development
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

package.json

@@ -40,7 +40,7 @@
   },
   "devDependencies": {
     "auto-changelog": "^2.2.0",
-    "c8": "^7.9.0",
+    "c8": "^8.0.0",
     "eslint": "^4.19.1",
     "eslint-config-mysticatea": "^13.0.2",
     "fs-extra": "^11.1.0",