chore(astro): Add astro-integration keyword

[Lms24]

Turns out, to make our Astro package show up in Astro's integration library, we need to add another keyword that's only mentioned here and not in Astro's NPM publishing guide.

With this keyword added (and once we cut the next release), our SDK should show up in the library 🤞

(I'd like to get this out relatively soonish so that we can write docs that actually use npx astro add as opposed to installing the package manually).

ref #9093

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser (incl. Tracing, Replay) - Webpack (gzipped)	83.98 KB (-0.34% 🔽)
@sentry/browser (incl. Tracing) - Webpack (gzipped)	31.57 KB (+0.48% 🔺)
@sentry/browser - Webpack (gzipped)	21.75 KB (-1.2% 🔽)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (gzipped)	80.47 KB (+2.15% 🔺)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (gzipped)	29.51 KB (+3.19% 🔺)
@sentry/browser - ES6 CDN Bundle (gzipped)	21.69 KB (+3.17% 🔺)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (minified & uncompressed)	245.55 KB (-3.53% 🔽)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (minified & uncompressed)	85.53 KB (-1.43% 🔽)
@sentry/browser - ES6 CDN Bundle (minified & uncompressed)	61.45 KB (-1.62% 🔽)
@sentry/browser (incl. Tracing) - ES5 CDN Bundle (gzipped)	32.64 KB (+3.69% 🔺)
@sentry/react (incl. Tracing, Replay) - Webpack (gzipped)	84.05 KB (-0.29% 🔽)
@sentry/react - Webpack (gzipped)	21.79 KB (-1.21% 🔽)
@sentry/nextjs Client (incl. Tracing, Replay) - Webpack (gzipped)	102.18 KB (-0.03% 🔽)
@sentry/nextjs Client - Webpack (gzipped)	49.65 KB (-2.57% 🔽)