plugin-astro peer dependency astro

When adding `@orama/plugin-astro`:

```
dependencies:
+ @orama/plugin-astro 3.0.5

 WARN  Issues with peer dependencies found
.
└─┬ @orama/plugin-astro 3.0.5
  └── ✕ unmet peer astro@^2.0.4: found 5.2.5
```

Version 2 is really old now...  Might as well upgrade.
