422 Over Nginx and WebSocket subscriptions transport

**go 1.22**
Packages:
```
github.com/99designs/gqlgen v0.17.46
github.com/gorilla/websocket v1.5.3
github.com/vektah/gqlparser v1.3.1
github.com/vektah/gqlparser/v2 v2.5.23
```

Client lib - `apollo` + `subscriptions-transport-ws`

Without Nginx it worked fine, but in production environment I receive such logs:

```
[6957]: time="2025-03-04T11:58:23+03:00" level=warning msg="GQL ERR no operation provided"
[6957]: time="2025-03-04T11:58:23+03:00" level=warning msg="Response Status: 422"
[6957]: time="2025-03-04T11:58:23+03:00" level=warning msg="Response Body: {\"errors\":[{\"message\":\"no operation provided\",\"extensions\":{\"code\":\"GRAPHQL_VALIDATION_FAILED\"}}],\"data\":null}"

```

Even with `wscat` tool I can establish connections without a problem but only directly to golang server.

A issue envolve WebSocket subscriptions com gqlgen e Nginx. Comece examinando a gqlgen WebSocket transport configuration e as Nginx proxy settings para WebSocket support. Verifique os server logs para o erro 'no operation provided'. Teste WebSocket connections diretamente para o Go server e através do Nginx para reproduzir a 422 response.

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