DEV: adding codespace configuration
I added the [dev container configuration](https://docs.github.com/en/codespaces/setting-up-your-project-for-codespaces/adding-a-dev-container-configuration/introduction-to-dev-containers) so a codespace opened on the pandas repo would auto-install the environment.
Seems that the `setup.sh` script needs executable permissions - `chmod +x` should do the trick. Also the `.devcontainer.json` file in the root of the repository should be replaced with this one, so you'll need to delete that file. This pull request is stale because it has been open for thirty days with no activity. Please [update](https://pandas.pydata.org/pandas-docs/stable/development/contributing.html#updating-your-pull-request) and respond to this comment if you're still interested in working on this. This PR conflicts with our infrastructure for using Docker with a remote session with Visual Studio Code. Since the previous comment mentioned we would need to replace one with the other, I suggest I close this one.  
@craiglpeters if there is a way to keep both, please let us know and we will re-open this PR.