Permission denied issue on snap install adguard-home

### Prerequisites

- [X] I have checked the [Wiki](https://github.com/AdguardTeam/AdGuardHome/wiki) and [Discussions](https://github.com/AdguardTeam/AdGuardHome/discussions/categories/q-a) and found no answer

- [X] I have searched other issues and found no duplicates

- [X] I want to report a bug and not [ask a question or ask for help](https://github.com/AdguardTeam/AdGuardHome/discussions/categories/q-a)

- [X] I have set up AdGuard Home correctly and [configured clients to use it](https://github.com/AdguardTeam/AdGuardHome/wiki/Clients). (Use the [Discussions](https://github.com/AdguardTeam/AdGuardHome/discussions/categories/q-a) for help with installing and configuring clients.)

### Platform (OS and CPU architecture)

Ubuntu 22.04.3 LTS arm64

### Installation

GitHub releases or script from README

### Setup

On one machine

### AdGuard Home version

v0.107.40

### Action

permission denied when applying path of privkey.pem

### Expected result

config saved

### Actual result

permission denied

### Additional information and/or screenshots

1st pic showed that adguard can access /etc/let*/live to view the fullchain.pem without permission issue

2nd pic showed that when tried to paste the path of privkey.pem, then permission denied