Missing flutter version for MacOS dev setup docs

The [issue](https://github.com/AppFlowy-IO/AppFlowy/issues/3154) is from the main AppFlowy repo.

> ### Bug Description
>
> While I was building from source I faced an issue with the Flutter version.
> ### How to Reproduce
>
> While trying to build from source in MacOS using the [link](https://docs.appflowy.io/docs/essential-documentation/contribute-to-appflowy/software-contributions/environment-setup/building-on-macos)
> ### Expected Behavior
>
> A requirement at the top of the build instructions should be available showing the currently supported version of flutter, rust, and other dependencies for a successful build.
> ### Operating System
>
> MacOS
> ### AppFlowy Version(s)
>
> 0.2.8
> ### Screenshots
>
> ### Additional Context
>
> _No response_

While the flutter version is not specified in the [docs](https://docs.appflowy.io/docs/documentation/appflowy/from-source/environment-setup/building-on-macos). The script scripts/install_dev_env/install_macos.sh automates the fetching of the flutter version and specifies which version to use.

The flutter version is specifically mentioned in both the [linux](https://docs.appflowy.io/docs/documentation/appflowy/from-source/environment-setup/building-on-linux#install-flutter-three-different-methods) and [windows](https://docs.appflowy.io/docs/documentation/appflowy/from-source/environment-setup/building-on-windows#step-2-install-your-build-environment) doc.

Open the MacOS build documentation linked in the issue and compare its dependency instructions with scripts/install_dev_env/install_macos.sh, which fetches the Flutter version. Update the documentation to state the supported Flutter version and the other required dependency versions, matching the existing Linux and Windows guidance.

Written by the indexing model from the issue text.