Update workflows to include arm build platform

[stanleegoodspeed]

This will publish arm and amd versions of the images to fix some local build issues when using tagged ECR images. I tested the arm context locally via the following cmd:

docker build --platform linux/arm64 --tag public.ecr.aws/x2b9z2t7/storedog/backend:arm-test-1 --no-cache ./services/backend

Additionally I updated the docker compose to have the correct subnet CIDR block

Checklist

Before you move on, make sure that:

• No unintended changes are included
• Spelling is correct
• There are tests covering new/changed functionality
• Commits have meaningful names and changes. CR remarks-like commits are squashed.
• Proper labels assigned. Use WIP label to indicate that state

[devindford]

Apple silicon 🙃