Graphviz tooltips are rendered inconsistently from `dot` to `ojs`

[cscheid]

Minimal repro:

---
title: "test graphviz"
---

```{ojs}
dot`graph G {
    a [tooltip="Tooltip for a"]
    b [tooltip="Tooltip for b"]
    c [tooltip="Tooltip for c"]
    d [tooltip="Tooltip for d"]
    a -- b;
    b -- c;
    c -- d;
    d -- a;
}`
```

```{dot}
graph G {
    a [tooltip="Tooltip for a"]
    b [tooltip="Tooltip for b"]
    c [tooltip="Tooltip for c"]
    d [tooltip="Tooltip for d"]
    a -- b;
    b -- c;
    c -- d;
    d -- a;
}
```