Update typescript-eslint monorepo to v8

Author: renovate[bot]

package.json

@@ -25,8 +25,8 @@
     "@types/highlight.js": "^9.12.3",
     "@types/katex": "^0.11.0",
     "@types/marked": "^0.7.3",
-    "@typescript-eslint/eslint-plugin": "^2.26.0",
-    "@typescript-eslint/parser": "^2.26.0",
+    "@typescript-eslint/eslint-plugin": "^8.0.0",
+    "@typescript-eslint/parser": "^8.0.0",
     "babel-plugin-preval": "^5.0.0",
     "eslint": "^6.8.0",
     "eslint-config-prettier": "^6.10.1",