MyQ failing to persist accessories to disk 
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**Describe The Problem:**
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I’m seeing errors in Homebridge logs around failing to persist accessories to disk. I’ve narrowed down MyQ as the plugin creating the error. I uninstalled the plugin and the issue went away. I reinstalled and the issue came back when adding the garage door accessories to Homebridge.

**To Reproduce:**
<!-- Steps to reproduce the behavior. -->
1. Install MyQ plugin for Homebridge
2. Configure plugin with MyQ account
3. Restart Homebridge
4. View homebridge logs

**Logs:**
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```

[8/18/2021, 9:14:05 AM] [myQ] Medz Main: Adding garagedoor device to HomeKit: [[Redacted]].
[8/18/2021, 9:14:05 AM] Failed to save cached accessories to disk: Converting circular structure to JSON
    --> starting at object with constructor 'Timeout'
    |     property '_idlePrev' -> object with constructor 'TimersList'
    --- property '_idleNext' closes the circle
[8/18/2021, 9:14:05 AM] Your accessories will not persist between restarts until this issue is resolved.
[8/18/2021, 9:14:05 AM] Failed to save cached accessories to disk: Converting circular structure to JSON
    --> starting at object with constructor 'Timeout'
    |     property '_idlePrev' -> object with constructor 'TimersList'
    --- property '_idleNext' closes the circle
[8/18/2021, 9:14:05 AM] Your accessories will not persist between restarts until this issue is resolved.
[8/18/2021, 9:14:05 AM] [myQ] Third Car: Adding garagedoor device to HomeKit: T [[Redacted]].
[8/18/2021, 9:14:05 AM] Failed to save cached accessories to disk: Converting circular structure to JSON
    --> starting at object with constructor 'Timeout'
    |     property '_idlePrev' -> object with constructor 'TimersList'
    --- property '_idleNext' closes the circle
[8/18/2021, 9:14:05 AM] Your accessories will not persist between restarts until this issue is resolved.
[8/18/2021, 9:14:05 AM] Failed to save cached accessories to disk: Converting circular structure to JSON
    --> starting at object with constructor 'Timeout'
    |     property '_idlePrev' -> object with constructor 'TimersList'
    --- property '_idleNext' closes the circle
[8/18/2021, 9:14:05 AM] Your accessories will not persist between restarts until this issue is resolved.
```

**Environment:**

* **Node.js Version**:  v14.17.5
* **NPM Version**: v6.14.14
* **Homebridge Version**: v1.3.4
* **Operating System**: Raspbian GNU/Linux Buster (10)
* **Process Supervisor**: Systemd
* **Homebridge-myQ Plugin Version**: homebridge-myq v2.6.5
* **Apple Device and iOS / macOS / iPadOS / tvOS Version:** iPad & iPadOS 14.7.1

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