Update portainer/portainer-ce Docker tag to v2.26.1

Author: renovate[bot]

docker-compose-monitoring.yaml

@@ -2,7 +2,7 @@ version: '2.4'
 
 services:
   portainer:
-    image: portainer/portainer-ce:2.19.4-alpine
+    image: portainer/portainer-ce:2.26.1-alpine
     command:
       - "--admin-password-file"
       - "/tmp/portainer_password"