Add DB Screen fonts

flake.nix

@@ -75,6 +75,13 @@
             license = licenses.ofl;
             author = "Pablo Impallari and Alexi Vanyashin";
           }
+          {
+            # Deutsche Bahn website font
+            name = "DB Screen";
+            dir = ./DB-Screen;
+            license = licenses.unfree;
+            author = "URW Type Foundry";
+          }
           {
             # Popular font, used on Amtrak
             name = "Frutiger";