Cert is not accepted by Traefik

## Environment

* Operating system (including version): Ubuntu 24.04.3 LTS
* mkcert version (from `mkcert -version`): 1.4.4
* Server (where the certificate is loaded): Docker/Traefik
* Client (e.g. browser, CLI tool, or script): Firefox Snap 142.0.1

## What you did

After installing mkcert, i startet by `mkcert -install` and generated some certs by `sudo mkcert -cert-file /opt/containers/traefik/certs/svcinternal-cert.pem -key-file /opt/containers/traefik/certs/svcinternal-cert-key.pem *.homebox.lan`.
After that, I installed docker and traefik with the following files

traefik.yml
```yml
global:
checkNewVersion: true
sendAnonymousUsage: false

log:
# DEBUG, PANIC, FATAL, ERROR, WARN, and INFO.
level: DEBUG

api:
dashboard: true

entryPoints:
http:
address: ":80"
https:
address: ":443"

providers:
docker:
endpoint: "unix:///var/run/docker.sock"
exposedByDefault: false
file:
filename: "/dynamic.yml"
watch: true
```

and a dynamic.yml

```yml
tls:
certificates:
- certFile: /etc/certs/svcinternal-cert.pem
keyFile: /etc/certs/svcinternal-cert-key.pem

http:
middlewares:
# secHeaders@file
# - Set Sameorigin
# - Set HSTS
# - enforce HTTPS
secHeaders:
headers:
browserXssFilter: true
contentTypeNosniff: true
customFrameOptionsValue: "SAMEORIGIN"
sslRedirect: true
#HSTS Configuration
stsIncludeSubdomains: true
stsPreload: true
stsSeconds: 15552000
```

and configured the compose like this

```yml
services:
traefik:
image: traefik:latest
container_name: traefik
restart: unless-stopped
security_opt:
- no-new-privileges:true
ports:
- 80:80
- 443:443
environment:
- LEGO_EXPERIMENTAL_CNAME_SUPPORT=true
labels:
- "traefik.enable=true"
- "com.centurylinklabs.watchtower.enable=true"
- "traefik.http.routers.api.entrypoints=https"
- "traefik.http.routers.api.rule=Host(`traefik.homebox.lan`)"
- "traefik.http.routers.api.tls=true"
- "traefik.http.routers.api.service=api@internal"
- "traefik.http.routers.traefik.middlewares=secHeaders@file"

volumes:
- /etc/localtime:/etc/localtime:ro
- /var/run/docker.sock:/var/run/docker.sock:ro
- ./config/traefik.yml:/traefik.yml:ro
- ./config/dynamic.yml:/dynamic.yml:ro
- ./certs:/etc/certs:ro
- ./log:/var/log
networks:
- proxy

networks:
proxy:
external: true
```

## What went wrong

As soon as i want to reach the URL (also happens with other URLs), the certificate is only accepted as a self-signed certificate. I also got the following info by letting traefik run without daemon:

`remote error: tls: unknown certificate authority`

I also can see, that the mkcert development CA is available within the certification manager of firefox. If I ignore the warning and trust the self-signed certificate, traefik-dashboard (or other services) can be accessed.