Input converted to a list when it is not

### What happened?

Hello all. I have a schema describing github repository, and each repository has a field `admins`, which is of type `[Account]`. `[Account]` in my case is an interface, thus `admins` is a list of interfaces:

The respective graphql (excerpt) is as follows:
```graphql
interface Account {
...
}

type GithubUserAccount implements Account {
# CID is github id of form "https://github.com/[handle]"
cid: ID!
name: String
}

type GithubRepository {
cid: ID!
...
admins: [Account!]
}

```

and the generated resolvers are

```golang
type Account interface {
IsAccount()
...
}

type AccountCreateInput struct {
// Cid acts as ID
Cid *string `json:"cid,omitempty"`
GithubUserAccount *GithubUserAccountCreateInput `json:"GithubUserAccount,omitempty"`
...
}

type GithubRepositoryCreateInput struct {
Cid string `json:"cid"`
...
Admins []*AccountCreateInput `json:"admins"
}
```

Now, when I try to do an insertion via the following query:
```
mutation testMutation($input: GithubRepositoryCreateInput!) {
createGithubRepository(input: $input) {
...
}
}
```

with vars:
```
"input": {
"cid": "testrepo",
"admins": {
"GithubUserAccount": {
"cid": "alice",
"name": "alice"
},
"GithubUserAccount": {
"cid": "bob",
"name": "bob"
},
"GithubUserAccount": {
"cid": "carol",
"name": "carol"
}
}
}
}
```
Only `Carol` is created as an account, and the input is implicitly converted to a list:
```
model.GithubRepositoryCreateInput {testrepo testurl 0x400039a140 [] [] [] [] [] [0x400006df80] [] [] [] [] [] [] }
```
(admins are the field `[0x400006df80]` corresponding to a `[]*model.AccountCreateInput`)

If I pass a correct input as below, three users are created:
```
{
"input": {
"cid": "testrepo",
"admins": [
{
"GithubUserAccount": {
"cid": "alice",
"name": "alice"
}
},
{
"GithubUserAccount": {
"cid": "bob",
"name": "bob"
}
},
{
"GithubUserAccount": {
"cid": "carol",
"name": "carol"
}
}
]
}
}
```

### What did you expect?
I would expect a GraphQL validation error.

### versions
- `go run github.com/99designs/gqlgen version`: `v0.17.22`
- `go version`: `go1.19.7 linux/arm64`