Update ote-events to sticky version

https://tools.opentechevents.org/embed/

Currently using
```html

````

Sticky version:
```html

```

Or fixed to latest (it could break if spec changes)
```html

```

Search the repository for the current https://tools.opentechevents.org/embed/ote-events.js reference and inspect the page or component that contains it. Update the widget source to the specified v0.3.0 sticky URL, then verify the rendered page or project build uses that exact URL.

索引モデルが issue の本文から書いたものです。