When both yaml and json tags are present (with differing configuration), yaml takes precedence, cannot be changed

I have a struct that looks like:

```
type Example struct {
	ItemId  string `json:"item_id,omitempty" yaml:"-"`
}
```

When generating using tygo, the `ItemId` field is always ignored (not present in the final generated .ts file). It seems that yaml tags override json tags. 