Update Flutter SDK Dependencies

[Ariflo]

As reported on issue https://github.com/magiclabs/magic-flutter/issues/45 our Flutter SDK which currently depends on agent_dart v1.0.0-dev.15 cannot run on the latest iOS development platform.

This PR does the following to address the issues:

• Forks the secp256r1 dependency we use for DPoP and updates the agent_dart dependency to the latest v1.0.0-dev.18 where the parseErrorData described in issue https://github.com/magiclabs/magic-flutter/issues/45 has been resolved

• Applies all the subsequent updates required with the move to v1.0.0-dev.18 (ie. web3dart > 2.7.0, package_info_plus >^4.2.0, Solana > 0.30.0)

• Updates demo app to match latest versioning, one caveat being @Ethella I need collaboration access to your fork => https://github.com/Ethella/tezart to update this line, this line, and this line.

More notes:

• These updates DO NOT resolve the problem with running our SDK with the latest version of iOS 😢 . I've posted an issue with: secp256r1, Apple, and agent_dart in hopes that the development community can help me resolve this issue.

• That said, this solution works on Android, and ergo may still be worth releasing to our developers.

[shortcut-integration[bot]]

This pull request has been linked to Shortcut Story #89220: [Magic Flutter] parseErrorData must be provided with Magic Flutter SDK.

[Ariflo]

More notes: These updates DO NOT resolve the problem with running our SDK with the latest version of iOS 😢 . I've posted an >issue with: https://github.com/AstroxNetwork/flutter_secp256r1/issues/7, [Apple]>(https://developer.apple.com/forums/thread/738672?login=true&page=1#771390022), and https://github.com/AstroxNetwork/agent_dart/issues/71 in hopes that the development community can help me resolve this issue. That said, this solution works on Android, and ergo may still be worth releasing to our developers.

@Ethella agent_dart developer resolved our issue with iOS, this PR now works on both platforms. 🎊