Run multiline workflow steps inside Nix

Co-authored-by: dichhead <330471626+dichhead@users.noreply.github.com>

.github/workflows/weekly-release.yml

@@ -43,13 +43,15 @@ jobs:
           GH_TOKEN: ${{ github.token }}
           PUBLISH: ${{ github.event_name == 'schedule' || inputs.publish }}
         run: |
-          nix develop --command bash --noprofile --norc -euo pipefail <<'EOF'
+          SCRIPT=$(cat <<'EOF'
           if [ "$PUBLISH" = true ]; then
             python3 scripts/release.py prepare --publish
           else
             python3 scripts/release.py prepare
           fi
           EOF
+          )
+          nix develop --command bash --noprofile --norc -euo pipefail -c "$SCRIPT"
 
   # GITHUB_TOKEN releases do not trigger release events, so call both builds.
   web: