Change d4r license to GPL-3.0-only

packaging/D4R_README.txt

@@ -128,7 +128,7 @@ cache in ~/.cache/d4r can be deleted too.
 
 Licenses
 --------
-d4r is Apache License 2.0. The release also contains ZLUDA (Apache 2.0 or MIT), vkd3d-proton
+d4r is GNU General Public License, version 3 only (GPL-3.0-only). The release also contains ZLUDA (Apache 2.0 or MIT), vkd3d-proton
 (LGPL 2.1, patched) and OptiScaler 0.9.4 (GPL 3.0, unmodified). d4r/source/SOURCES.txt says where
 each file comes from, and d4r/licenses has the license texts. d4r is not affiliated with NVIDIA,
 AMD or the OptiScaler project.