[CI] Gracefully Fail when Job Completion Timestamp is None

There seem to be cases where the workflow status is completed but the
jobs have not completed. We need to gracefully handle these changes to
avoid a crash loop in the metrics container.

Author: boomanaiden154

.ci/metrics/metrics.py

@@ -370,6 +370,13 @@ def github_get_metrics(
             started_at = job.started_at
             completed_at = job.completed_at
 
+            if completed_at is None:
+                logging.info(
+                    "Workflow {} is marked completed but has a job without a "
+                    "completion timestamp."
+                )
+                continue
+
             # GitHub API can return results where the started_at is slightly
             # later then the created_at (or completed earlier than started).
             # This would cause a -23h59mn delta, which will show up as +24h