openmolcas: fix license

pkgs/applications/science/chemistry/openmolcas/default.nix

···
     description = "Advanced quantum chemistry software package";
     homepage = "https://gitlab.com/Molcas/OpenMolcas";
     maintainers = [ maintainers.markuskowa ];
-    license = licenses.lgpl21;
+    license = licenses.lgpl21Only;
     platforms = [ "x86_64-linux" ];
   };
 }