Trying to install/update from Homebridge UI results in Error: forkpty(3) failed.
**Describe The Bug:**
When trying to install/update anything I see this message:
![image](https://user-images.githubusercontent.com/4789510/133512640-28be7ebb-14c3-4ac2-b3d2-fa605a3c5f74.png)

**To Reproduce:**
- open shell on Fritz!Box 6591 (Fritz!OS 7.28, [modified](https://bitbucket.org/fesc2000/ffritz/src/6591/), within buildroot)
- install [node-v16.10.0](https://unofficial-builds.nodejs.org/download/release/v16.10.0/node-v16.10.0-linux-x86.tar.xz)
- run `npm install -g --unsafe-perm homebridge homebridge-config-ui-x`
- reinstall hb from UI

**Expected behavior:**
`npm` executes like it does from a plain shell

[**Logs:**]()
```
Will post any if you ask for it.
```

**Homebridge Config:**
```json
Plain standard.
```

**Screenshots:**
See above.

**Environment:**

* **Node.js Version**: v16.10.0
* **NPM Version**: 8.0.0
* **Homebridge Version**: v1.3.5
* **Operating System**: Linux fritz.box 4.9.250 # 1 SMP PREEMPT 2021-04-12 i686
* **Process Supervisor**: hb-service

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