Update rust when building libavif

Author: radarhere

winbuild/build_prepare.py

@@ -389,6 +389,7 @@ def cmd_msbuild(
         "filename": f"libavif-{V['LIBAVIF']}.zip",
         "license": "LICENSE",
         "build": [
+            "rustup update",
             f"{sys.executable} -m pip install meson",
             *cmds_cmake(
                 "avif_static",