Update install.yml

roles/custom/matrix-element-call/tasks/install.yml

@@ -88,7 +88,7 @@
 
 - name: Ensure redis Docker image is pulled
   community.docker.docker_image:
-    name: "{{ matrix_redis_image }}"
+    name: "{{ redis_image }}"
     source: pull
   register: redis_image_result
   retries: 3