Use SHA-1 instead of major versions for actions in the F-Droid workflow

.github/workflows/upload_fdroid_apks.yml

@@ -11,10 +11,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout mobile code
-        uses: actions/checkout@v6
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
 
       - name: Set up JDK 17
-        uses: actions/setup-java@v5
+        uses: actions/setup-java@be666c2fcd27ec809703dec50e508c2fdc7f6654 # v5.2.0
         with:
           java-version: 17
           distribution: temurin
@@ -23,7 +23,7 @@ jobs:
         run: echo "FLUTTER_VERSION=$(cat flutter-version)" >> $GITHUB_ENV
 
       - name: Install Flutter
-        uses: subosito/flutter-action@v2
+        uses: subosito/flutter-action@1a449444c387b1966244ae4d4f8c696479add0b2 # v2.23.0
         with:
           flutter-version: ${{ env.FLUTTER_VERSION }}
 
@@ -63,7 +63,7 @@ jobs:
           flutter build apk --split-per-abi --target-platform="android-arm64" --dart-define=cronetHttpNoPlay=true --dart-define=LICHESS_HOST=lichess.org --dart-define=LICHESS_WS_HOST=socket.lichess.org --dart-define=LICHESS_WS_SECRET=wG1OLhUR3CSXdDybqrtIW227QGrtiM3d
 
       - name: Configure AWS credentials
-        uses: aws-actions/configure-aws-credentials@v6
+        uses: aws-actions/configure-aws-credentials@d979d5b3a71173a29b74b5b88418bfda9437d885 # v6.1.1
         with:
           aws-access-key-id: ${{ secrets.S3_ACCESS_KEY }}
           aws-secret-access-key: ${{ secrets.S3_SECRET_KEY }}