Run services as non-root

[j08lue]

It would be great to understand, which of our eoAPI services run as root in their respective containers, and where we can change that to a regular user.

Some platforms require this as better security practice.

[pantierra]

I identified all services running as root and created PRs on the upstream repos to fix that:

• Add non-root user for Docker container. stac-utils/stac-fastapi-pgstac#312
• Add non-root user for container. stac-utils/titiler-pgstac#237
• Add non-root user for container. tipg#242
• Add non-root user for container. titiler-md-demo#11
• Add non-root user for container. stac-utils/pgstac#390
• Run container as non-root user radiantearth/stac-browser#727

The check-images.sh script allow to verify.