Replace country_pickers to an updated package

[deandreamatias]

Environment

Package name: form_builder_phone_field
Package version: 1.0.0-beta.0
Platform: All
Device information: N/A

Description

What you'd like to happen: Replace dependency country_pickers, because these package don't receive more update

Alternatives you've considered:

• https://github.com/Daniel-Ioannou/flutter_country_picker
• https://github.com/dev-naiksan/country-calling-code-picker
• https://github.com/imtoori/CountryCodePicker
• https://github.com/hifiaz/country-list-pick

[deandreamatias]

Related issue flutter-form-builder-ecosystem/flutter_form_builder#346