MAINT: Fix Parcels alpha release uploads (#2542)

Author: VeckoTheGecko

.github/workflows/ci.yml

@@ -212,7 +212,7 @@ jobs:
         run: |
           for pkg in $(find output -type f \( -name "*.conda" -o -name "*.tar.bz2" \) ); do
             echo "Uploading ${pkg}"
-            rattler-build upload prefix -c parcels "${pkg}"
+            pixi run -e rattler-build rattler-build upload prefix -c parcels "${pkg}"
           done
         env:
           PREFIX_API_KEY: ${{ secrets.PREFIX_API_KEY }}