Fix conda upload: try without --force first, fallback to --force

The --force flag causes prefix.dev to return 500 "Package version does
not exist" on first upload of a new version. Upload without --force
first (works for new versions), then retry with --force (works for
re-uploads of existing versions).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Entire-Checkpoint: e95a79181772

Author: facontidavide

.github/workflows/conda.yaml

@@ -82,8 +82,12 @@ jobs:
         shell: bash
         run: |
           shopt -s nullglob globstar
+          EXIT_CODE=0
           for pkg in artifacts/**/*.conda artifacts/**/*.tar.bz2; do
             echo "Uploading ${pkg}"
-            rattler-build upload prefix --force -c plotjuggler "${pkg}" || \
-              echo "::warning::Failed to upload ${pkg} (may already exist on prefix.dev)"
+            if ! rattler-build upload prefix -c plotjuggler "${pkg}" && \
+               ! rattler-build upload prefix --force -c plotjuggler "${pkg}"; then
+              EXIT_CODE=1
+            fi
           done
+          exit $EXIT_CODE