Update ci.yml

Author: lucafluri

.github/workflows/ci.yml

@@ -10,6 +10,9 @@ on:
       - master
       - dev
 
+env:
+  FLUTTER_VERSION: "1.22.1"
+
 jobs:
   # This workflow contains a single job called "build"
   test:
@@ -22,7 +25,7 @@ jobs:
     - uses: actions/checkout@v2
     - uses: actions/setup-java@v1
       with:
-        java-version: '12.x'
+        java-version: '13.x'
     - uses: subosito/flutter-action@v1.3.2
       with:
         channel: 'stable' # or: 'dev' or 'beta'