feat: gitea: vendor + fix heatmap

package/gitea/source/services/mailer/sender/sender.go

@@ -0,0 +1,31 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package sender
+
+import (
+	"errors"
+	"io"
+)
+
+type Sender interface {
+	Send(from string, to []string, msg io.WriterTo) error
+}
+
+var Send = send
+
+func send(sender Sender, msg *Message) error {
+	m := msg.ToMessage()
+	froms := m.GetFrom()
+	to, err := m.GetRecipients()
+	if err != nil {
+		return err
+	}
+
+	// TODO: implement sending from multiple addresses
+	if len(froms) == 0 {
+		// FIXME: no idea why sometimes the "froms" can be empty, need to figure out the root problem
+		return errors.New("no FROM specified")
+	}
+	return sender.Send(froms[0].Address, to, m)
+}