package.json: Restrict eslint-plugin-react to 7.28.x

With 7.29 we get some bogus `react/jsx-indent` errors due to some
mis-parsing. We'll need to update the whole ESLint suite at some point,
but we can't do that yet because at least there is no available
eslint-plugin-standard release which works with eslint 8.

package.json

@@ -31,7 +31,7 @@
     "eslint-plugin-jsx-a11y": "^6.5.1",
     "eslint-plugin-node": "^11.1.0",
     "eslint-plugin-promise": "^5.1.0",
-    "eslint-plugin-react": "^7.23.0",
+    "eslint-plugin-react": "~7.28.0",
     "eslint-plugin-react-hooks": "^4.1.2",
     "eslint-plugin-standard": "^4.0.1",
     "eslint-webpack-plugin": "^2.5.3",