Incompatible with Gatsby v4

[LucyMac]

I unfortunately can't use this plugin because I'm still on Gatsby v4. Would it break if this line were changed?

From:

  "peerDependencies": {
    "gatsby": "^5.0.0"
  }

To:

"peerDependencies": {
    "gatsby": "^5.0.0 || ^4.0.0"
  }

Happy to open a PR.