Migrate to use jsoniter instead of encoding/json (#14841)

* Migrate to use jsoniter

* fix tests

* update gitea.com/go-chi/binding

Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: 6543 <6543@obermui.de>

modules/private/mail.go

@@ -5,12 +5,12 @@
 package private
 
 import (
-	"encoding/json"
 	"fmt"
 	"io/ioutil"
 	"net/http"
 
 	"code.gitea.io/gitea/modules/setting"
+	jsoniter "github.com/json-iterator/go"
 )
 
 // Email structure holds a data for sending general emails
@@ -32,6 +32,7 @@ func SendEmail(subject, message string, to []string) (int, string) {
 
 	req := newInternalRequest(reqURL, "POST")
 	req = req.Header("Content-Type", "application/json")
+	json := jsoniter.ConfigCompatibleWithStandardLibrary
 	jsonBytes, _ := json.Marshal(Email{
 		Subject: subject,
 		Message: message,