Update to podspec file

[tabrezp]

Instead of making use of resource_bundles, I have changed it to use resources. This fixes the issue wherein the builds uploaded to TestFlight from Xcode 13 don't show up the flag icons.

[scy0334]

@tabrezp Seems your pull request has not been merged yet. So how can I update it manually on my XCode TT?

[jorgtz]

This creates an error when building:

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Multiple commands produce '/Users/user/Library/Developer/Xcode/DerivedData/myapp-deihxwhjfkxfeofoygvcqusvdtbn/Build/Products/DebugStag-iphonesimulator/myapp.app/Assets.car'

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That command depends on command in Target 'myapp' (project 'myapp'): script phase “[CP] Copy Pods Resources”

How to fix this ?