fix validation app dir name

Author: yiyuan-he

.github/workflows/release-udp-exporter.yml

@@ -96,7 +96,7 @@ jobs:
           pip install ./exporters/aws-otel-otlp-udp-exporter/dist/*.whl
 
       - name: Run validation test
-        working-directory: exporters/aws-otel-otlp-udp-exporter/validation_app
+        working-directory: exporters/aws-otel-otlp-udp-exporter/validation-app
         run: python app.py
 
       - name: Verify X-Ray daemon received traces