これやればいいだろー。
flutter clean rm .packages rm -rf ~/Library/Developer/Xcode/DerivedData rm ios/Podfile.lock rm -rf ios/Runner.xcworkspace/ cd ios pod deintegrate pod install open ./Runner.xcworkspace/
またはFVMなら
.fvm/flutter_sdk/bin/flutter clean rm .packages rm -rf ~/Library/Developer/Xcode/DerivedData rm ios/Podfile.lock rm -rf ios/Runner.xcworkspace/ cd ios pod deintegrate pod install open ./Runner.xcworkspace/
さらにXcodeで shift + command + K