Will not minimize to tray

**Describe the bug**
CopyQ stops minimizing to tray.

**To Reproduce**
**Note:** I am not completely sure about this:

Steps to reproduce the behavior:

1. Log in with auto start on and minimize to tray on
2. Wait for some time.
3. CopyQ windows is suddenly open and minimized to dock
4. Only way to make it minimize to tray is to close CopyQ and start it again.

I will update this if I find out more.

**Expected behavior**
I expect the windows to minimize to tray.

**Screenshots**
N/A

**Version, OS and Environment**
(Get details from `copyq version` command if possible.)

- **Application Version:** 6.0.1~focal
- **OS:** Ubuntu
- **Desktop environment, window manager:** Gnome

```
$ copyq version
CopyQ Clipboard Manager 6.0.1~focal
Qt: 5.12.8
KNotifications: 5.68.0
Compiler: GCC
Arch: x86_64-little_endian-lp64
OS: Ubuntu 20.04.3 LTS
```

**Additional context**
Add any other context about the problem here.