DDR doesn't announce h3 support if serve_http3 is set

### 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)

Linux, ARM64

### Installation

Snapcraft

### Setup

On one machine

### AdGuard Home version

v0.108.0-a.780+75cb9d41

### Action

```shell
$ grep serve_http3 /var/snap/adguard-home/current/AdGuardHome.yaml
serve_http3: true
$ dig +short @192.168.78.58 _dns.resolver.arpa type64
1 192.168.78.58. alpn="h2" port=443 key7="/dns-query{?dns}"
1 192.168.78.58. alpn="h2" port=443 key7="/dns-query{?dns}"
1 192.168.78.58. alpn="dot" port=853
1 192.168.78.58. alpn="dot" port=853
1 192.168.78.58. alpn="doq" port=853
1 192.168.78.58. alpn="doq" port=853
```

### Expected result

`alpn="h2,h3"`

(also, maybe no duplicated answers)

### Actual result

`alpn="h2"`

### Additional information and/or screenshots

_No response_