Run core tests in Safari. Partially addresses https://github.com/pyodide/pyodide/issues/989

It runs, but there are several test failures, I'll open separate issues about those.
---
name: Feature request
about: Suggest an idea for Pyodide
title: ""
labels: enhancement
assignees: ""
---

## 🚀 Feature

<!-- A clear and concise description of the feature proposal -->

### Motivation

<!-- Please outline the motivation for the proposal. Is your feature request related to a problem? e.g., I'm always frustrated when [...]. If this is related to another GitHub issue, please link here too -->

### Pitch

<!-- A clear and concise description of what you want to happen. -->

### Alternatives

<!-- A clear and concise description of any alternative solutions or features you've considered, if any. -->

### Additional context

<!-- Add any other context or screenshots about the feature request here. -->

---
name: Feature request
about: Suggest an idea for Pyodide
title: ""
labels: enhancement
assignees: ""
---

## 🚀 Feature

<!-- A clear and concise description of the feature proposal -->

### Motivation

<!-- Please outline the motivation for the proposal. Is your feature request related to a problem? e.g., I'm always frustrated when [...]. If this is related to another GitHub issue, please link here too -->

### Pitch

<!-- A clear and concise description of what you want to happen. -->

### Alternatives

<!-- A clear and concise description of any alternative solutions or features you've considered, if any. -->

### Additional context

<!-- Add any other context or screenshots about the feature request here. -->
