gnu: nsis: Use scons 3 over scons-python2

Rather than building NSIS with Scons 3 using Python2, switch to Scons
3 with Python 3.

From c49419c7dc262f81d664fcab4c7fd200d3627c05 Mon Sep 17 00:00:00 2001
From: fanquake <fanquake@gmail.com>
Date: Mon, 29 Jul 2024 11:55:07 +0100
Subject: [PATCH] gnu: nsis: Use scons 3 over scons-python2

Signed-off-by: Zheng Junjie <zhengjunjie@iscas.ac.cn>

gnu/packages/installers.scm

@@ -49,7 +49,7 @@
                        ("mingw-w64" ,xlibc)))
       (inputs (list zlib))
       (arguments
-       `(#:scons ,scons-python2
+       `(#:scons ,scons-3
          #:modules ((srfi srfi-1)
                     (srfi srfi-26)
                     (guix build utils)