chore(deps-dev): bump @textlint/ast-tester from 2.3.5 to 12.0.0

Bumps [@textlint/ast-tester](https://github.com/textlint/textlint) from 2.3.5 to 12.0.0.
- [Release notes](https://github.com/textlint/textlint/releases)
- [Changelog](https://github.com/textlint/textlint/blob/master/CHANGELOG.md)
- [Commits](https://github.com/textlint/textlint/compare/@textlint/ast-tester@2.3.5...v12.0.0)

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -42,7 +42,7 @@
         "structured-source": "^3.0.2"
     },
     "devDependencies": {
-        "@textlint/ast-tester": "^2.3.4",
+        "@textlint/ast-tester": "^12.0.0",
         "@types/chai": "^4.2.4",
         "@types/mocha": "^8.0.0",
         "@types/node": "^15.0.0",