Add OTA fallback for gallery embed

Pre-update native builds don't recognize app.bsky.embed.gallery (Photos
v2, >4 images). Bump @atproto/api to 0.20.9 so the OTA bundle can parse
the embed, and render a friendly "Something new is here" prompt with the
photo count and a link to bsky.app/download in place of the unrenderable
gallery. Native-only; web ships with full gallery support in the same
release.

APP-2308

(cherry picked from commit f9023f48b1)

package.json

@@ -92,7 +92,7 @@
     "icons:optimize": "svgo -f ./assets/icons"
   },
   "dependencies": {
-    "@atproto/api": "0.20.8",
+    "@atproto/api": "0.20.9",
     "@atproto/syntax": "0.6.1",
     "@bitdrift/react-native": "^0.6.8",
     "@braintree/sanitize-url": "^6.0.2",