增加vendor

vendor/github.com/silenceper/wechat/v2/util/signature.go

@@ -0,0 +1,18 @@
+package util
+
+import (
+	"crypto/sha1"
+	"fmt"
+	"io"
+	"sort"
+)
+
+// Signature sha1签名
+func Signature(params ...string) string {
+	sort.Strings(params)
+	h := sha1.New()
+	for _, s := range params {
+		_, _ = io.WriteString(h, s)
+	}
+	return fmt.Sprintf("%x", h.Sum(nil))
+}