Fix localization in pretix

pkgs/pretix/pretix.nix

@@ -1,6 +1,7 @@
 { lib
 , poetry2nix
 , pkgs
+, gettext
 , tlds-alpha-by-domain ? ./tlds-alpha-by-domain.txt
 }:
 
@@ -44,6 +45,17 @@ poetry2nix.mkPoetryApplication rec {
             preBuild = "cp ${tlds-alpha-by-domain} ./tlds-alpha-by-domain.txt";
           }
         );
+        pretix = super.pretix.overridePythonAttrs (
+          old: {
+            buildInputs = (old.buildInputs or [ ]) ++ [
+              gettext
+            ];
+            preFixup = ''
+              python -m pretix compilemessages
+              python -m pretix compilejsi18n
+            '';
+          }
+        );
       }
     );
 }