🐛 Environment variable replacement in the `baseURL` not applied during signing

[Thomasvdam]

🐛 Bug Report

Environment variable replacement in the baseURL is not applied when signing the request URL.

Steps to Reproduce

Set up a Data Proxy with a baseURL using environment variable replacement and make a request.

Code snippet to reproduce

{
  "routeGroup": "proxy",
  "baseURL": "{$PROXY_URL}",
  "routes": [
    {
      "path": "/planets/:planet",
      "upstreamUrl": "https://swapi.dev/api/planets/{:planet}",
      // Now the API will also return the server header from SWApi
      "forwardResponseHeaders": ["content-type", "server"],
      "headers": {
        "x-api-key": "some-api-key"
      }
    }
  ]
}

Stack trace & error message

Invalid signature

Expected Behavior

BaseURL should be evaluated properly, resulting in a valid signature.