Update react-native-sensitive-info to v6

[WouterFlorijn]

From the docs on v6:

This version uses by default keystore to encrypt/decrypt data on Android.

This should mean that using the keystore branch is no longer necessary.

The upgrade should include a major version update of this package, as it is not backwards compatible.

[vganenco]

Yes, add support for v6, please

[mkilp]

I openend a PR #31 for this. Hopefully it gets merged!

[manoj398]

From the docs on v6:

This version uses by default keystore to encrypt/decrypt data on Android.

This should mean that using the keystore branch is no longer necessary.

The upgrade should include a major version update of this package, as it is not backwards compatible.

peerDependencies should be changed to "3.x - 6.x" and this small change should be minor version update.