GitHub CI does not runs on ubuntu instead of alpine

Author: Michael Vasseur

.github/workflows/build-domjudge-container-release.yml

@@ -38,7 +38,7 @@ jobs:
             echo "I don't know which version to pick!"
             exit 1
           fi
-          apk add jq curl
+          sudo apt update; sudo apt install jq curl -y
           set -x
             HUBURL="https://registry.hub.docker.com/v2/repositories/domjudge/domserver/tags"
             TAG=$(curl $HUBURL|jq '.results | sort_by(.name) | .[length-2].name')