kaldi-vosk-server. Wget don't trust let's encrypt certs

## Environment

| docker | CPU | OS | RAM |
|----------|------------------------------------------|------------------------------|------|
| v20.10.8 | Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz | Darwin Kernel Version 20.6.0 | 16GB |

## Summary

Wget in vosk-server image (digest: `7d556d01f565`) couldn't download sites with let's encrypt certs (including alphacep website), due to wget certificate error.

## Steps to reproduce

```bash
docker run alphacep/kaldi-vosk-server wget https://letsencrypt.org
```

## Expected

wget successfully downloads let's encrypt index page

## Actual result

```bash
Resolving letsencrypt.org (letsencrypt.org)... 161.35.218.92, 167.99.246.105, 2a03:b0c0:3:d0::143f:a001, ...
Connecting to letsencrypt.org (letsencrypt.org)|161.35.218.92|:443... connected.
GnuTLS: Resource temporarily unavailable, try again.
GnuTLS: Resource temporarily unavailable, try again.
GnuTLS: Resource temporarily unavailable, try again.
ERROR: The certificate of 'letsencrypt.org' is not trusted.
ERROR: The certificate of 'letsencrypt.org' has expired.
```