Merge pull request RustPython#4433 from lgyanf/devcontainer

[RFC] Add Github Codespaces configuration (devcontainer.json)

Author: youknowone

.devcontainer/devcontainer.json

@@ -0,0 +1,6 @@
+{
+  "image": "mcr.microsoft.com/devcontainers/universal:2",
+  "features": {
+    "ghcr.io/devcontainers/features/rust:1": {}
+  }
+}