sql.value does not support arrays
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### Summary

sql.value renders arrays as objects, not arrays

### Steps to reproduce

Pass an array to sql.value when constructing a SQL statement (e.g. through resolveInfo.graphile.selectGraphQLResultsFromTable).  Observe the SQL error that results.

### Expected results

A successful query against a `json` type in Postgres.

### Actual results

I don't know how to get postgraphile to show me the raw query it's generating, but the error indicates it's rendering an array using "{}" syntax instead of "[]" syntax.

```
postgres-plato_1  | 2021-11-01 18:28:47.580 UTC [191] ERROR:  invalid input syntax for type json
postgres-plato_1  | 2021-11-01 18:28:47.580 UTC [191] DETAIL:  Expected ":", but found "}".
postgres-plato_1  | 2021-11-01 18:28:47.580 UTC [191] CONTEXT:  JSON data, line 1: {"0"}
```

### Additional context

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### Possible Solution

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