Enable fix float point 2 decimal place

### What happened?
If the type is of type `Float` or `Decimal` (custom from https://github.com/shopspring/decimal) and the value have trailing zero, it will not show the trailing zero.
Eg 191.80 is showing as 191.8

### What did you expect?
191.80 Supposed to show 191.80

### Minimal graphql.schema and models to reproduce
even when implementing MarshalGQL (for decimal) doesnt work.

func (y Decimal) MarshalGQL(w io.Writer) {
fmt.Fprintf(w, decimal.Decimal(y).StringFixed(2))
}

### versions
- `go run github.com/99designs/gqlgen version`?
v0.17.45
- `go version`?
1.21.5