flutter_stripe custom stripe-ios local dependency

Question

I would like to use a modify version of stripe_ios library in flutter_stripe library to include a missing functionality I added.

for that I downloaded both libraries and copy them inside a packages directory of my flutter app.

then inside pubspec.yaml I declared the library like that:

flutter_stripe:
    path: packages/stripe

then in flutter_stripe library folder I edited stripe_ios/ios/stripe_ios.podspec to make Stripe library reference point to my modified version:

Pod::Spec.new do |s|
  s.name             = 'stripe_ios'
  s.version          = '0.0.1'
  s.summary          = 'A new flutter plugin project.'
  s.description      = <<-DESC
A new flutter plugin project.
                       DESC
  s.homepage         = 'http://example.com'
  s.license          = { :file => '../LICENSE' }
  s.author           = { 'Your Company' => '[email protected]' }
  s.source           = { :path => '.' }
  s.source_files = 'Classes/**/*'
  s.dependency 'Flutter'
  s.dependency 'Stripe'
  s.subspec 'Stripe' do |ss|
    ss.source_files = '../../library/StripeIos/Stripe'
  end
  s.platform = :ios, '11.0'

  # Flutter.framework does not contain a i386 slice.
  s.pod_target_xcconfig = { 'DEFINES_MODULE' => 'YES', 'EXCLUDED_ARCHS[sdk=iphonesimulator*]' => 'i386' }
  s.swift_version = '5.0'
end

But it seems it's not working correctly and when I do pod install from ios folder it seems to download version 21.13.0 of Stripe ios library instead.

any idea how to achieve this correctly ?