v8.0 module release (#22975)

https://mattermost.atlassian.net/browse/MM-52079

```release-note
We upgrade the module version to 8.0. The new module path is github.com/mattermost-server/server/v8.
```


Co-authored-by: Doug Lauder <wiggin77@warpmail.net>

server/model/push_response_test.go

@@ -0,0 +1,24 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package model
+
+import (
+	"testing"
+)
+
+func TestNewOkPushResponse(t *testing.T) {
+	r := NewOkPushResponse()
+	CheckString(t, r["status"], "OK")
+}
+
+func TestNewRemovePushResponse(t *testing.T) {
+	r := NewRemovePushResponse()
+	CheckString(t, r["status"], "REMOVE")
+}
+
+func TestNewErrorPushResponse(t *testing.T) {
+	r := NewErrorPushResponse("error message")
+	CheckString(t, r["status"], "FAIL")
+	CheckString(t, r["error"], "error message")
+}