Update Flutter submodule and make GitHub actions error out if it doesn't match latest/stable

.github/workflows/release.yml

@@ -23,6 +23,17 @@ jobs:
           gpg_private_key: ${{ secrets.PGP_KEY_BASE64 }}
           passphrase: ${{ secrets.PGP_PASSPHRASE }}
 
+      - name: Check submodule
+        id: check_submodule
+        run: |
+          SUBMODULE_COMMIT="$(cd .flutter; git rev-parse --short HEAD; cd ..)"
+          FLUTTER_COMMIT="$(flutter --version | head -2 | tail -1 | awk '{print $4}')"
+          echo "SUBMODULE_COMMIT=$SUBMODULE_COMMIT, FLUTTER_COMMIT=$FLUTTER_COMMIT"
+          if [ "$SUBMODULE_COMMIT" != "$FLUTTER_COMMIT" ]; then
+            echo "Your submodule has not been updated!"
+            exit 1
+          fi
+
       - name: Extract Version
         id: extract_version      
         run: |

build.sh

@@ -7,6 +7,9 @@ trap "cd "$CURR_DIR"" EXIT
 if [ -z "$1" ]; then
     git fetch && git merge origin/main && git push # Typically run after a PR to main, so bring dev up to date
 fi
+cd .flutter
+git checkout "$(flutter --version | head -2 | tail -1 | awk '{print $4}')" # Ensure included Flutter submodule version equals my environment
+cd ..
 rm ./build/app/outputs/flutter-apk/* 2>/dev/null                                       # Get rid of older builds if any
 flutter build apk --flavor normal && flutter build apk --split-per-abi --flavor normal # Build (both split and combined APKs)
 for file in ./build/app/outputs/flutter-apk/app-*normal*.apk*; do mv "$file" "${file//-normal/}"; done