Allow cmake<4 when building libavif

Author: radarhere

winbuild/build_prepare.py

@@ -395,6 +395,7 @@ def cmd_msbuild(
                 "-DAVIF_CODEC_DAV1D=LOCAL",
                 "-DAVIF_CODEC_RAV1E=LOCAL",
                 "-DAVIF_CODEC_SVT=LOCAL",
+                "-DCMAKE_POLICY_VERSION_MINIMUM=3.5",
             ),
             cmd_xcopy("include", "{inc_dir}"),
         ],