fix broken tests report when there are no fails

Author: strtgbb

.github/actions/create_workflow_report/create_workflow_report.py

@@ -249,6 +249,9 @@ def get_checks_known_fails(
 
     df = client.query_dataframe(query)
 
+    if df.shape[0] == 0:
+        return df
+
     df.insert(
         len(df.columns) - 1,
         "reason",