neomutt: fix STARTTLS

When smtps is used as a protocol, neomutt expects TLS but will if
STARTTLS should be used. When using STARTTLS, smtp has to be used as
protocol and `ssl_force_tls` is set.

See <https://neomutt.org/guide/optionalfeatures#2-1-%C2%A0starttls>.

modules/programs/neomutt.nix

@@ -118,7 +118,8 @@ let
       sendmail = "'${neomutt.sendMailCommand}'";
     } else
       let
-        smtpProto = if smtp.tls.enable then "smtps" else "smtp";
+        smtpProto =
+          if smtp.tls.enable && !smtp.tls.useStartTls then "smtps" else "smtp";
         smtpPort = if smtp.port != null then ":${toString smtp.port}" else "";
         smtpBaseUrl =
           "${smtpProto}://${escape userName}@${smtp.host}${smtpPort}";
@@ -217,7 +218,9 @@ let
         }";
     in ''
       # Generated by Home Manager.
-      set ssl_force_tls = yes
+      set ssl_force_tls = ${
+        lib.hm.booleans.yesNo (smtp.tls.enable || smtp.tls.useStartTls)
+      }
       set certificate_file=${toString config.accounts.email.certificatesFile}
 
       # GPG section