Use correct JUnit path

Author: JoshMock

.buildkite/pipeline.yml

@@ -17,7 +17,7 @@ steps:
           - "18"
           - "20"
     command: ./.buildkite/run-tests.sh
-    artifact_paths: "*junit.xml"
+    artifact_paths: "junit-output/*junit.xml"
   - wait: ~
     continue_on_failure: true
   - label: "Test results"