增加vendor

vendor/github.com/silenceper/wechat/v2/cache/cache.go

@@ -0,0 +1,11 @@
+package cache
+
+import "time"
+
+// Cache interface
+type Cache interface {
+	Get(key string) interface{}
+	Set(key string, val interface{}, timeout time.Duration) error
+	IsExist(key string) bool
+	Delete(key string) error
+}