Minor changes to run go 1.18 in codespaces

[mesolimbo]

The title says it on, I tested this out on the latest codespaces with a basic helloworld app.

[mesolimbo]

I switched to a simpler devcontainer config inspired by this repo but using all the latest codespaces bells and whistles:

{
    "name": "Codespace for Golang with copilot",
    "image": "mcr.microsoft.com/devcontainers/go:1.20-bullseye",
    "hostRequirements": {
        "cpus": 4
    },
    "customizations": {
        "vscode": {
            "extensions": [
                "coenraads.bracket-pair-colorizer-2",
                "eamodio.gitlens",
                "GitHub.copilot",
                "github.vscode-pull-request-github",
                "golang.go",
                "ms-azuretools.vscode-docker",
                "ms-vscode.go",
                "ms-vsliveshare.vsliveshare",
                "visualstudioexptteam.vscodeintellicode",
                "vscode-icons-team.vscode-icons"
            ],
            "settings": {
                "files.exclude": {
                    "**/CODE_OF_CONDUCT.md": true,
                    "**/LICENSE": true
                }
            }
        }
    },
    "features": {
        "ghcr.io/devcontainers/features/docker-in-docker:2": {},
        "ghcr.io/jungaretti/features/make:1": {},
        "ghcr.io/devcontainers/features/sshd:1": { "version": "latest" }
    }
}