Use mattermost v5 module (#1192)

vendor/github.com/mattermost/mattermost-server/v5/model/channel_stats.go

@@ -0,0 +1,27 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package model
+
+import (
+	"encoding/json"
+	"io"
+)
+
+type ChannelStats struct {
+	ChannelId       string `json:"channel_id"`
+	MemberCount     int64  `json:"member_count"`
+	GuestCount      int64  `json:"guest_count"`
+	PinnedPostCount int64  `json:"pinnedpost_count"`
+}
+
+func (o *ChannelStats) ToJson() string {
+	b, _ := json.Marshal(o)
+	return string(b)
+}
+
+func ChannelStatsFromJson(data io.Reader) *ChannelStats {
+	var o *ChannelStats
+	json.NewDecoder(data).Decode(&o)
+	return o
+}