feat: use dummy pusher by default (#1349)

internal/push/offlinepush/dummy/push.go

@@ -0,0 +1,17 @@
+package dummy
+
+import (
+	"context"
+	"github.com/openimsdk/open-im-server/v3/internal/push/offlinepush"
+)
+
+func NewClient() *Dummy {
+	return &Dummy{}
+}
+
+type Dummy struct {
+}
+
+func (d *Dummy) Push(ctx context.Context, userIDs []string, title, content string, opts *offlinepush.Opts) error {
+	return nil
+}