fix(deps): bump expo from 54.0.12 to 54.0.21 in /examples/expo

Bumps [expo](https://github.com/expo/expo/tree/HEAD/packages/expo) from 54.0.12 to 54.0.21.
- [Changelog](https://github.com/expo/expo/blob/main/packages/expo/CHANGELOG.md)
- [Commits](https://github.com/expo/expo/commits/HEAD/packages/expo)

---
updated-dependencies:
- dependency-name: expo
  dependency-version: 54.0.21
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

examples/expo/package.json

@@ -17,7 +17,7 @@
     "@react-navigation/elements": "^2.6.3",
     "@react-navigation/native": "^7.1.8",
     "axios": "^1.12.2",
-    "expo": "~54.0.12",
+    "expo": "~54.0.21",
     "expo-constants": "~18.0.9",
     "expo-dev-client": "~6.0.13",
     "expo-font": "~14.0.8",