feat(ci): push container images to ghcr.io as well (#10945)

## Problem
There's new rate-limits coming on docker hub. To reduce our reliance on
docker hub and the problems the limits are going to cause for us, we
want to prepare for this by also pushing our container images to ghcr.io

## Summary of changes
Push our images to ghcr.io as well and not just docker hub.

scripts/generate_image_maps.py

@@ -27,6 +27,7 @@ components = {
 registries = {
     "dev": [
         "docker.io/neondatabase",
+        "ghcr.io/neondatabase",
         f"{dev_aws}.dkr.ecr.{aws_region}.amazonaws.com",
         f"{dev_acr}.azurecr.io/neondatabase",
     ],