gxmessage: update homepage and source URLs

and use SPDX 3.0 license identifier

pkgs/applications/misc/gxmessage/default.nix

@@ -5,7 +5,7 @@ stdenv.mkDerivation rec {
   version = "3.4.3";
 
   src = fetchurl {
-    url = "http://homepages.ihug.co.nz/~trmusson/stuff/${pname}-${version}.tar.gz";
+    url = "https://trmusson.dreamhosters.com/stuff/${pname}-${version}.tar.gz";
     sha256 = "db4e1655fc58f31e5770a17dfca4e6c89028ad8b2c8e043febc87a0beedeef05";
   };
 
@@ -14,8 +14,8 @@ stdenv.mkDerivation rec {
 
   meta = {
     description = "A GTK enabled dropin replacement for xmessage";
-    homepage = "http://homepages.ihug.co.nz/~trmusson/programs.html#gxmessage";
-    license = lib.licenses.gpl3;
+    homepage = "https://trmusson.dreamhosters.com/programs.html#gxmessage";
+    license = lib.licenses.gpl3Plus;
     maintainers = with lib.maintainers; [jfb];
     platforms = with lib.platforms; linux;
   };