Fix docs url in tests (#13992)

https://github.com/apache/airflow/pull/13250 missed a case to update
URL in `tests/www/test_views.py`.

(cherry picked from commit 9840e406fd)

tests/www/test_views.py

@@ -499,7 +499,7 @@ class TestAirflowBaseViews(TestBase):
                 "http://apache-airflow-docs.s3-website.eu-central-1.amazonaws.com/docs/apache-airflow/"
             )
         else:
-            airflow_doc_site = f'https://airflow.apache.org/docs/{version.version}'
+            airflow_doc_site = f'https://airflow.apache.org/docs/apache-airflow/{version.version}'
 
         self.check_content_in_response(airflow_doc_site, resp)
         self.check_content_in_response("/api/v1/ui", resp)