Bump devcontainer OS version

[spenserblack]

buster is out-of-date and comes with an old version of Rust.

[spenserblack]

I haven't had a chance to test this out yet, but it should work. I'll test it out later when I get a chance.

[o2sh]

Here is the error I'm getting when running cargo run

[spenserblack]

Weird, I thought I made a PR to fix this. Must have written the code but not actually made the PR 😅

This can be resolved with cargo update time. It's currently affecting everyone with a recent version of the compiler installed AFAIK, not just this devcontainer.