fix: fallback to 'price' in ecommerce api loader

The Django Oscar upgrade of ecommerce changed the
item's price field from price_excl_tax to just price
causing the EcommerceApi data loader to fail.

This commit handles the exception and falls back to
the 'price' value.

Ref: openedx-unsupported/ecommerce#4050

.github/workflows/ci.yml

@@ -44,7 +44,7 @@ jobs:
         continue-on-error: ${{ matrix.status == 'ignored' }}
       - name: Upload coverage
         if: matrix.db-version == 'mysql80'
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
           name: coverage${{ matrix.pytest-split-group }}
           path: .coverage

course_discovery/apps/course_metadata/data_loaders/api.py

@@ -572,7 +572,7 @@ def update_seats(self, body):
     def update_seat(self, course_run, product_body):
         stock_record = product_body['stockrecords'][0]
         currency_code = stock_record['price_currency']
-        price = Decimal(stock_record['price_excl_tax'])
+        price = Decimal(stock_record.get('price_excl_tax', stock_record['price']))
         sku = stock_record['partner_sku']
 
         # For more context see ADR docs/decisions/0025-dont-sync-mobile-skus-on-discovery.rst