Remove usage of ::set-output in GitHub Actions (#1422)

Author: stof

.github/workflows/branch_alias.yml

@@ -23,7 +23,7 @@ jobs:
           echo "Last tag was $TAG"
           ARR=(${TAG//./ })
           ARR[1]=$((${ARR[1]}+1))
-          echo ::set-output name=alias::${ARR[0]}.${ARR[1]}
+          echo "alias=${ARR[0]}.${ARR[1]}" >> $GITHUB_OUTPUT
 
       - name: Checkout main repo
         run: |