Provide a --force-ipv4 parameter

[pabloab]

Prerequisites

• [x ] Did you make sure a similar issue didn't exist?
• [x ] Did you update gTTS to the latest? (pip install --upgrade gTTS)

Proposed Behaviour

I had the same problem with both three: gtts-cli, streamlink and youtube-dl: They stuck at some point for some minutes. Solution: streamlink: --ipv4 , youtube-dl: --force-ipv4. Probably related to IPv6 DNS lookups.

Surely, we can force IPv4 user or system-wide, but would be nice to have a --force-ipv4 parameter on gtts-cli.

This was useful to reveal the issue: nmap -Pn -p80,443 -6 youtube.com; nmap -4 youtube.com.