🛠 Make automatically recognize new versions

[kimlulz]

1. Changed git url https://github.com/cdr/code-server -> https://github.com/coder/code-server
2. Added the process of checking the released latest version using Github API. So, It doesn't need to manually modify the version in the dockerfile.

      VERSION=$(curl -sX GET https://api.github.com/repos/coder/code-server/releases/latest \

wget https://github.com/coder/code-server/releases/download/v${VERSION}/code-server-${VERSION}-linux-amd64.tar.gz && \
tar x -zf code-server-${VERSION}-linux-amd64.tar.gz && \

Need to test, but i think it will work properly