Ensure that the devcontainer.json is valid JSON

[zigsphere]

Currently, the devcontainer.json template file is invalid JSON resulting in a failed JSON parser error if people have a JSON parser in their CI/CD pipeline. Fixing this to avoid this issue moving forward when updating or creating a module with PDK.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[chelnak]

Hey, thanks!