bump to go 1.20 + fix some code issues

mail/mail.go

@@ -3,11 +3,12 @@ package mail
 import (
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
+	"os"
 	"strings"
 )
 
 type Email struct {
+	Path      string
 	Sender    string   `json:"sender"`
 	Receivers []string `json:"receivers"`
 	Subject   string   `json:"subject"`
@@ -26,9 +27,9 @@ func NewEmail(sender string, receivers []string, subject, content string) Email
 func FromJSON(path string) (Email, error) {
 	var mail Email
 
-	content, err := ioutil.ReadFile(path)
+	content, err := os.ReadFile(path)
 	if err != nil {
-		return mail, err
+		return mail, fmt.Errorf("%w, unable to read the file: %s", err, path)
 	}
 
 	if err := json.Unmarshal(content, &mail); err != nil {