immich - extract flutter version

metadata/app.alextran.immich.yml

@@ -2228,7 +2228,7 @@ Builds:
       - apt-get install -y gcc-multilib libc-dev make
     output: build/app/outputs/flutter-apk/app-release.apk
     srclibs:
-      - flutter@3.13.2
+      - flutter@stable
       - rustup@1.25.2
     rm:
       - design
@@ -2238,6 +2238,10 @@ Builds:
       - server
       - web
     prebuild:
+      - export flutterVersion=$(sed -n -E 's/.*flutter-version:\s"([0-9.]+)"/\1/p' ../.github/workflows/build-mobile.yml)
+      - pushd $$flutter$$
+      - git checkout -f $flutterVersion
+      - popd
       - export PUB_CACHE=$(pwd)/.pub-cache
       - sed -i -e "s/^\#f//" pubspec.yaml
       - sed -i -e 's/^\/\/f //' android/app/build.gradle