Update Synapse (v0.33.4 -> v0.33.5.1)

roles/matrix-server/defaults/main.yml

@@ -122,7 +122,7 @@ matrix_docker_image_postgres_v9: "postgres:9.6.10-alpine"
 matrix_docker_image_postgres_v10: "postgres:10.5-alpine"
 matrix_docker_image_postgres_latest: "{{ matrix_docker_image_postgres_v10 }}"
 
-matrix_docker_image_synapse: "matrixdotorg/synapse:v0.33.4"
+matrix_docker_image_synapse: "matrixdotorg/synapse:v0.33.5.1"
 matrix_docker_image_nginx: "nginx:1.15.3-alpine"
 matrix_docker_image_riot: "avhost/docker-matrix-riot:v0.16.4"
 matrix_docker_image_goofys: "cloudproto/goofys:latest"