refactor(tools): switch to Nix

- Nix is more reproducible (pinned to a specific hash)
- Faster rebuild after changing the package list (due to /nix caching in volume)
- Users can still use make tools (wrapped in Docker) without installing Nix
- Using nix-shell will work if you have nix installed.

scripts/wait-main-apps

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 
 import requests