python3Packages.pymavlink: license should be lgpl3Plus

The license file doesn't specify that later versions can be used, but I missed
that it is stated in the README: "pymavlink is released under the GNU Lesser
General Public License v3 or later."

pkgs/development/python-modules/pymavlink/default.nix

@@ -22,7 +22,7 @@ buildPythonPackage rec {
   meta = with lib; {
     description = "Python MAVLink interface and utilities";
     homepage = "https://github.com/ArduPilot/pymavlink";
-    license = with licenses; [ lgpl3Only mit ];
+    license = with licenses; [ lgpl3Plus mit ];
     maintainers = with maintainers; [ lopsided98 ];
   };
 }