CI: Add test for uploads with multiple labels

* Add test uploads for non-main label 'test' and for multiple labels in
  a comma seperated list. As attempting to apply multiple labels through
  repeated upload of the same package will fail as the package already
  exists, bump the version number of the test package to generate
  multiple packages that can be uploaded with different labels.

.github/workflows/ci.yml

@@ -36,7 +36,7 @@ jobs:
 
       - name: Build a wheel and a sdist
         run: |
-          PYTHONWARNINGS=error,default::DeprecationWarning python -m build --outdir ./dist tests/test_package
+          python -m build --outdir ./dist tests/test_package
 
       - name: Verify the distribution
         run: twine check --strict dist/*
@@ -53,6 +53,34 @@ jobs:
           artifacts_path: dist
           anaconda_nightly_upload_token: ${{ secrets.UPLOAD_TOKEN }}
 
+      - name: Build a wheel and a sdist
+        run: |
+          # Bump version to avoid wheel name conflicts
+          sed -i 's/0.0.1/0.0.2/g' tests/test_package/pyproject.toml
+          rm ./dist/*
+          python -m build --outdir ./dist tests/test_package
+
+      - name: Test upload with non-main label
+        uses: ./
+        with:
+          artifacts_path: dist
+          anaconda_nightly_upload_token: ${{ secrets.UPLOAD_TOKEN }}
+          anaconda_nightly_upload_labels: test
+
+      - name: Build a wheel and a sdist
+        run: |
+          # Bump version to avoid wheel name conflicts
+          sed -i 's/0.0.2/0.0.3/g' tests/test_package/pyproject.toml
+          rm ./dist/*
+          python -m build --outdir ./dist tests/test_package
+
+      - name: Test upload with multiple labels
+        uses: ./
+        with:
+          artifacts_path: dist
+          anaconda_nightly_upload_token: ${{ secrets.UPLOAD_TOKEN }}
+          anaconda_nightly_upload_labels: dev,test
+
   cleanup:
     runs-on: ubuntu-latest
     needs: [test]