allow test 12 to run on smslabs (fix x docker network mtu)

Author: sjpb

molecule/test12/molecule.yml

@@ -16,6 +16,10 @@ platforms:
       - /sys/fs/cgroup:/sys/fs/cgroup:ro
     networks:
       - name: net1
+    docker_networks:
+      - name: net1
+        driver_options:
+          com.docker.network.driver.mtu: ${DOCKER_MTU:-1500} # 1500 is docker default
   - name: testohpc-compute-0
     image: ${MOLECULE_IMAGE}
     pre_build_image: true