pkgs/pantheon: update meta.license

Based on project_license from appdata.

pkgs/desktops/pantheon/apps/elementary-screenshot/default.nix

@@ -71,7 +71,7 @@ stdenv.mkDerivation rec {
   meta = with lib; {
     description = "Screenshot tool designed for elementary OS";
     homepage = "https://github.com/elementary/screenshot";
-    license = licenses.lgpl3;
+    license = licenses.lgpl3Plus;
     platforms = platforms.linux;
     maintainers = teams.pantheon.members;
     mainProgram = "io.elementary.screenshot";

pkgs/desktops/pantheon/apps/elementary-terminal/default.nix

@@ -86,7 +86,7 @@ stdenv.mkDerivation rec {
       smart copy/paste, and little to no configuration.
     '';
     homepage = "https://github.com/elementary/terminal";
-    license = licenses.lgpl3;
+    license = licenses.lgpl3Plus;
     platforms = platforms.linux;
     maintainers = teams.pantheon.members;
     mainProgram = "io.elementary.terminal";

pkgs/desktops/pantheon/artwork/elementary-gtk-theme/default.nix

@@ -35,7 +35,7 @@ stdenv.mkDerivation rec {
   meta = with lib; {
     description = "GTK theme designed to be smooth, attractive, fast, and usable";
     homepage = "https://github.com/elementary/stylesheet";
-    license = licenses.gpl3;
+    license = licenses.gpl3Plus;
     platforms = platforms.linux;
     maintainers = teams.pantheon.members;
   };

pkgs/desktops/pantheon/artwork/elementary-icon-theme/default.nix

@@ -61,7 +61,7 @@ stdenv.mkDerivation rec {
       An original set of vector icons designed specifically for elementary OS and its desktop environment: Pantheon.
     '';
     homepage = "https://github.com/elementary/icons";
-    license = licenses.gpl3;
+    license = licenses.gpl3Plus;
     platforms = platforms.linux;
     maintainers = teams.pantheon.members;
   };