upgrade deps; rewrite smtp session

vendor/gitlab.com/etke.cc/go/secgen/password.go

@@ -2,6 +2,7 @@ package secgen
 
 import (
 	"crypto/rand"
+	"encoding/base64"
 	"math/big"
 	"strings"
 )
@@ -20,3 +21,10 @@ func Password(length int) string {
 
 	return password.String()
 }
+
+// Base64Bytes generates secure bytes with the given length and returns it as a base64 string
+func Base64Bytes(length int) string {
+	randomBytes := make([]byte, length)
+	rand.Read(randomBytes) //nolint:errcheck // nothing could be done anyway
+	return base64.StdEncoding.EncodeToString(randomBytes)
+}