Bump handlebars in /BrainJSReactNative/BrainJSReactNativeExampleApp

Bumps [handlebars](https://github.com/wycats/handlebars.js) from 4.0.11 to 4.7.1.
- [Release notes](https://github.com/wycats/handlebars.js/releases)
- [Changelog](https://github.com/wycats/handlebars.js/blob/v4.7.1/release-notes.md)
- [Commits](handlebars-lang/handlebars.js@v4.0.11...v4.7.1)

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