Rollback linter version to align with hello-world

Author: fcollonval

toolbar-button/package.json

@@ -49,13 +49,15 @@
   },
   "devDependencies": {
     "@jupyterlab/builder": "^3.0.0",
-    "@typescript-eslint/eslint-plugin": "^4.8.1",
-    "@typescript-eslint/parser": "^4.8.1",
-    "eslint": "^7.14.0",
-    "eslint-config-prettier": "^6.15.0",
-    "eslint-plugin-prettier": "^3.1.4",
+    "@typescript-eslint/eslint-plugin": "^2.27.0",
+    "@typescript-eslint/parser": "^2.27.0",
+    "eslint": "^7.5.0",
+    "eslint-config-prettier": "^6.10.1",
+    "eslint-plugin-jsdoc": "^22.0.0",
+    "eslint-plugin-prettier": "^3.1.2",
+    "eslint-plugin-react": "^7.18.3",
     "npm-run-all": "^4.1.5",
-    "prettier": "^2.1.1",
+    "prettier": "^1.19.0",
     "rimraf": "^3.0.2",
     "typescript": "~4.1.3"
   },