msmtp: fix passwordeval (#1643)

msmtp fails with broken pipe error when sending emails.
The new line after the password is not required anymore since msmtp 1.8.0.

modules/programs/msmtp.nix

@@ -26,9 +26,8 @@ let
         tls_fingerprint = msmtp.tls.fingerprint;
       } // optionalAttrs (smtp.port != null) { port = toString smtp.port; }
         // optionalAttrs (passwordCommand != null) {
-          # msmtp requires the password to finish with a newline.
           passwordeval =
-            ''${pkgs.bash}/bin/bash -c "${toString passwordCommand}; echo"'';
+            ''${pkgs.bash}/bin/bash -c "${toString passwordCommand}"'';
         } // msmtp.extraConfig) ++ optional primary ''
 
           account default : ${name}'');