[docker] Update opencti/connector-export-file-txt Docker tag to v6.9.20

Author: renovate[bot]

docker-compose.opensearch.yml

@@ -210,7 +210,7 @@ services:
       opencti:
         condition: service_healthy
   connector-export-file-txt:
-    image: opencti/connector-export-file-txt:6.9.6
+    image: opencti/connector-export-file-txt:6.9.20
     environment:
       - OPENCTI_URL=http://opencti:8080
       - OPENCTI_TOKEN=${OPENCTI_ADMIN_TOKEN}