Deal with some GHA deprecation warnings (#14216)

.github/workflows/docs.yaml

@@ -54,7 +54,7 @@ jobs:
           esac
 
           # finally, set the 'branch-version' var.
-          echo "::set-output name=branch-version::$branch"
+          echo "branch-version=$branch" >> "$GITHUB_OUTPUT"
           
       # Deploy to the target directory.
       - name: Deploy to gh pages

.github/workflows/release-artifacts.yml

@@ -34,7 +34,7 @@ jobs:
           if [[ $GITHUB_REF == refs/tags/* ]]; then
               dists=$(scripts-dev/build_debian_packages.py --show-dists-json)
           fi
-          echo "::set-output name=distros::$dists"
+          echo "distros=$dists" >> "$GITHUB_OUTPUT"
     # map the step outputs to job outputs
     outputs:
       distros: ${{ steps.set-distros.outputs.distros }}