Update RN version in example app to get rid off warning

[skusnierz]

Motivation

• Update RN version in example app to get rid off warning :

The following packages should be updated for best compatibility with the installed expo version:
  react-native@0.76.7 - expected version: 0.76.8
Your project may not work correctly until you install the expected versions of the packages.

• Add ios and android to .gitignore

[github-actions]

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