waagent: fix build

Use latest Python to avoid #353830

Co-authored-by: Sarah Stoltze <[email protected]>

Author: camelpunch

pkgs/by-name/wa/waagent/package.nix

@@ -2,13 +2,12 @@
   coreutils,
   fetchFromGitHub,
   lib,
-  python39,
+  python3,
   bash,
 }:
 
 let
-  # the latest python version that waagent test against according to https://github.com/Azure/WALinuxAgent/blob/28345a55f9b21dae89472111635fd6e41809d958/.github/workflows/ci_pr.yml#L75
-  python = python39;
+  python = python3;
 
 in
 python.pkgs.buildPythonApplication rec {