make the issuer use whatever path we've put the filesystem at

morph/lib/issuer.nix

@@ -56,6 +56,6 @@ in {
     ristrettoSigningKeyPath = config.deployment.secrets.ristretto-signing-key.destination;
     stripeSecretKeyPath = config.deployment.secrets.stripe-secret-key.destination;
     database = "SQLite3";
-    databasePath = "/var/lib/zkapissuer/vouchers.sqlite3";
+    databasePath = "${config.fileSystems."voucher-database".mountPoint}/vouchers.sqlite3";
   };
 }