Bump used flutter version to 3.19

.github/workflows/build-release.yml

@@ -26,7 +26,7 @@ jobs:
         uses: subosito/flutter-action@v2
         with:
           channel: stable
-          flutter-version: 3.16.x
+          flutter-version: 3.19.x
 
       - name: Flutter info
         run: |

.github/workflows/ci.yml

@@ -19,7 +19,7 @@ jobs:
         uses: subosito/flutter-action@v2
         with:
           channel: 'stable'
-          flutter-version: '3.16.x'
+          flutter-version: '3.19.x'
 
       - run: dart --version
       - run: flutter --version

.github/workflows/linter.yml

@@ -20,7 +20,7 @@ jobs:
         uses: subosito/flutter-action@v2
         with:
           channel: 'stable'
-          flutter-version: '3.16.x'
+          flutter-version: '3.19.x'
 
       - name: Get dependencies
         run: flutter pub get

README.md

@@ -43,7 +43,7 @@ Alternatively, you can use the test server (the db is reset every day):
 Install Flutter and all its dependencies, and create a new virtual device:
 <https://flutter.dev/docs/get-started/install>.
 
-The app currently uses flutter 3.16
+The app currently uses flutter 3.19
 
 ### 3
 The application will complain about an API key not being set. You can just