[chore] Adding Node 20 support for images exposed under mattermostdevelopment/mirrored-node (#26475)

Ticket: https://mattermost.atlassian.net/browse/CLD-7343

server/scripts/mirror-docker-images.json

@@ -36,6 +36,7 @@
     "16.17.0": "node:16.17.0",
     "18": "node:18@sha256:11e9c297fc51f6f65f7d0c7c8a8581e5721f2f16de43ceff1a199fd3ef609f95",
     "18.17": "node:18.17@sha256:11e9c297fc51f6f65f7d0c7c8a8581e5721f2f16de43ceff1a199fd3ef609f95",
-    "18.17.1": "node:18.17.1@sha256:11e9c297fc51f6f65f7d0c7c8a8581e5721f2f16de43ceff1a199fd3ef609f95"
+    "18.17.1": "node:18.17.1@sha256:11e9c297fc51f6f65f7d0c7c8a8581e5721f2f16de43ceff1a199fd3ef609f95",
+    "20.11.1": "node:20.11.1@sha256:e06aae17c40c7a6b5296ca6f942a02e6737ae61bbbf3e2158624bb0f887991b5"
   }
 }