Upgraded Demo App to support appwrite latest version

[DevTomilola-OS]

What does this PR do?

Upgraded flutter library to support appwrite latest version.

Test Plan

I reviewed and upraded the flutter library to suuport appwrite latest version before running.

Related PRs and Issues

closes issue#4275

Have you read the Contributing Guidelines on issues?

Yes

[codercatdev]

@DevTomilola-OS please see the file lib/data/service/api_service.dart this needs updates for types.
Please also see

One or more plugins require a higher Android SDK version.
Fix this issue by adding the following to /Users/ajonp/web/appwrite/demo-watertracker-with-flutter/android/app/build.gradle:
android {
  compileSdkVersion 33
  ...
}

[Meldiron]

Thank you so much for the PR 🤩. We're adding the hacktoberfest-accepted label to ensure this PR counts towards your Hacktoberfest contributions count. With that said, please stay active on this PR to address any comments once you receive a review. Happy Hacktoberfest! 🎃

[christyjacob4]

@DevTomilola-OS please address the comments

[codercatdev]

@DevTomilola-OS were you able to make this update?

[christyjacob4]

@DevTomilola-OS thanks a lot for your contributions during Hacktoberfest 2022!

Please reach out to me on our Discord server if you would like to claim your Appwrite swags! As a way of saying thank you, we would also love to invite you to join the Appwrite organization on GitHub. Please share your GitHub username with us on Discord. 

I'm closing this PR as there has not been any activity in here for a while. If you'd like to work on it again, please feel free to create a new PR.