[BUG] makeRequest debugging causes exception
**Describe the bug**

It appears the debugging part of [_makeRequest](https://github.com/arendruni/homebridge-pihole/blob/03acb5cfd66f3c8f030927d5ac8ab560e419c41f/src/index.ts#L142) function is causing an issue:

```
TypeError: Converting circular structure to JSON
    --> starting at object with constructor 'TLSSocket'
    |     property '_httpMessage' -> object with constructor 'ClientRequest'
    --- property 'socket' closes the circle
    at JSON.stringify (<anonymous>)
    at PiholeSwitch._makeRequest (/usr/lib/node_modules/homebridge-pihole/src/index.ts:161:11)
    at processTicksAndRejections (internal/process/task_queues.js:93:5)
    at On.<anonymous> (/usr/lib/node_modules/homebridge-pihole/src/index.ts:120:19)
(node:2381729) UnhandledPromiseRejectionWarning: Error: This callback function has already been called by someone else; it can only be called one time.
    at /usr/lib/node_modules/homebridge/node_modules/hap-nodejs/src/lib/util/once.ts:6:13
    at On.<anonymous> (/usr/lib/node_modules/homebridge-pihole/src/index.ts:132:7)
    at processTicksAndRejections (internal/process/task_queues.js:93:5)
```

Specifically, it seems the `config` is where the circular reference is coming from (inferred from typings of [AxiosResponse](https://github.com/axios/axios/blob/199c8aab64c45532389f3e56a913017a54803dfe/index.d.ts#L83) and [AxiosRequestConfig](https://github.com/axios/axios/blob/199c8aab64c45532389f3e56a913017a54803dfe/index.d.ts#L50)).

I'm going to open a PR in a few minutes to (hopefully) fix this by creating a custom `request`/`config` attribute that doesn't attempt to read Axios' config structure.

**To Reproduce**
Steps to reproduce the behavior:
1. Run the plugin

**Expected behavior**
Anything

**Desktop (please complete the following information):**
 - OS: Ubuntu 20.04
 - Browser n/a
 - Version: Latest

