fix: increase flutter version to 3.38.1

Author: sneurlax

docs/building.md

@@ -77,7 +77,7 @@ pip3 install --upgrade meson==0.64.1 markdown==3.4.1 markupsafe==2.1.1 jinja2==3
 ```
 
 ### Flutter
-Install Flutter 3.35.7 by [following their guide](https://docs.flutter.dev/get-started/install/linux/desktop?tab=download#install-the-flutter-sdk).  You can also clone https://github.com/flutter/flutter, check out the `3.35.7` tag, and add its `flutter/bin` folder to your PATH as in
+Install Flutter 3.38.1 by [following their guide](https://docs.flutter.dev/get-started/install/linux/desktop?tab=download#install-the-flutter-sdk).  You can also clone https://github.com/flutter/flutter, check out the `3.35.7` tag, and add its `flutter/bin` folder to your PATH as in
 ```sh
 FLUTTER_DIR="$HOME/development/flutter"
 git clone https://github.com/flutter/flutter.git "$FLUTTER_DIR"
@@ -293,13 +293,13 @@ If the DLLs were built on the WSL filesystem instead of on Windows, copy the res
 Frostdart will be built by the Windows host later.
 
 ### Install Flutter on Windows host
-Install Flutter 3.35.7 on your Windows host (not in WSL2) by [following their guide](https://docs.flutter.dev/get-started/install/windows/desktop?tab=download#install-the-flutter-sdk) or by cloning https://github.com/flutter/flutter, checking out the `3.35.7` tag, and adding its `flutter/bin` folder to your PATH as in
+Install Flutter 3.38.1 on your Windows host (not in WSL2) by [following their guide](https://docs.flutter.dev/get-started/install/windows/desktop?tab=download#install-the-flutter-sdk) or by cloning https://github.com/flutter/flutter, checking out the `3.38.1` tag, and adding its `flutter/bin` folder to your PATH as in
 ```bat
 @echo off
 set "FLUTTER_DIR=%USERPROFILE%\development\flutter"
 git clone https://github.com/flutter/flutter.git "%FLUTTER_DIR%"
 cd /d "%FLUTTER_DIR%"
-git checkout 3.35.7
+git checkout 3.38.1
 setx PATH "%PATH%;%FLUTTER_DIR%\bin"
 echo Flutter setup completed. Please restart your command prompt.
 ```