Update babel-eslint requirement from ^7.2.3 to ^9.0.0 (#67)

Updates the requirements on [babel-eslint](https://github.com/babel/babel-eslint) to permit the latest version.
- [Release notes](https://github.com/babel/babel-eslint/releases)
- [Commits](https://github.com/babel/babel-eslint/commits/v9.0.0)

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

package.json

@@ -36,7 +36,7 @@
     "nunjucks": "^3.0.0"
   },
   "devDependencies": {
-    "babel-eslint": "^7.2.3",
+    "babel-eslint": "^9.0.0",
     "chai": "^4.2.0",
     "cheerio": "^0.22.0",
     "eslint": "^2.4.0",