Add Python 3.10

[davetapley]

As given here and on #532 Python 3.10 has been released 🎉

Unfortunately:

manifest for mcr.microsoft.com/vscode/devcontainers/python:0-3.10 not found

which I assume because missing here ⬇️ ?

vscode-dev-containers/containers/python-3/definition-manifest.json

Line 2 in 85a9a2e

"variants": ["3", "3.9", "3.8", "3.7", "3.6"],

---

I think should be a simple bump (like 85a9a2e), because:

vscode-dev-containers/containers/python-3/.devcontainer/base.Dockerfile

Lines 1 to 3 in 85a9a2e

	# [Choice] Python version: 3, 3.9, 3.8, 3.7, 3.6
	ARG VARIANT=3
	FROM python:${VARIANT}

and python:3.10 tags are now on Dockerhub: https://hub.docker.com/_/python?tab=tags&page=1&name=3.10

Also note that python-3 on Dockerhub is now 3.10, see ENV PYTHON_VERSION=3.10.0 here,
so I presume rebuild would bump that as well? 🤔

---

If it's as simple as replicating 85a9a2e, then I'm happy to do a PR.

[Chuxel]

Happy to take a PR, and yes it is that simple. :) We can bump the 3 image as well and related definitions like python-3-postgres

[Chuxel]

PR #1108 will add in support once merged.

[davetapley]

Aw you beat me to it! Thanks 🙏🏻

[Chuxel]

Should be up now!