Update iOS target version

[MillerAdulu]

To use before the merge happens, update your pubspec.yaml file as follows:

dependencies:
  libphonenumber_plugin:

dependency_overrides:
  libphonenumber_plugin:
    git:
      url: https://github.com/natintosh/plugin_libphonenumber
      ref: d2a69be0e07dd62058898b1cc36b8a8cfecd15bb
      path: libphonenumber_plugin

[fwilliamconceicao]

@natintosh can you please merge?

[MillerAdulu]

@fwilliamconceicao @renatoalbsantos,

I have updated the description to allow you use this PR while waiting for the merge.