fix(bun): use npx for react-native-builder-bob in prepare script

Bun blocks lifecycle scripts by default for security. When users add the package
to trustedDependencies, the prepare script runs but bob is not available since
it's a devDependency. Using npx downloads bob on-demand.

Fixes #38

Author: mfazekas

package.json

@@ -38,7 +38,7 @@
     "typecheck": "tsc",
     "lint": "eslint \"**/*.{js,ts,tsx}\"",
     "clean": "del-cli android/build example/android/build example/android/app/build example/ios/build lib",
-    "prepare": "bob build",
+    "prepare": "npx react-native-builder-bob@^0.40.0 build",
     "nitrogen": "nitrogen",
     "release": "release-it",
     "dev:ios": "cd example && xed ios",