Updated react-scripts and eslint-plugin-ghost dependencies

refs https://github.com/TryGhost/Toolbox/issues/426

- this commit bumps both dependencies because it resolves various issues
  I've encountered when moving Portal to the Ghost monorepo

ghost/portal/package.json

@@ -25,7 +25,7 @@
     "@testing-library/user-event": "14.0.0",
     "react": "17.0.2",
     "react-dom": "17.0.2",
-    "react-scripts": "4.0.3"
+    "react-scripts": "5.0.1"
   },
   "scripts": {
     "start": "BROWSER=none react-scripts start",
@@ -78,7 +78,7 @@
     "chalk": "4.1.2",
     "chokidar": "3.5.3",
     "copy-webpack-plugin": "11.0.0",
-    "eslint-plugin-ghost": "2.12.0",
+    "eslint-plugin-ghost": "2.15.1",
     "minimist": "1.2.6",
     "ora": "5.4.1",
     "rewire": "6.0.0",