Use java 8

Author: borkdude

.github/workflows/ci.yml

@@ -20,5 +20,11 @@ jobs:
         with:
           babashka-version: 0.7.0
 
+      - uses: actions/checkout@v2
+      - uses: actions/setup-java@v2
+        with:
+          distribution: 'adopt'
+          java-version: '8'
+
       - name: Publish assets
         run: bb publish