fixed is_valid_public_ipv4 not working correctly when ipv6 is given as address

[endes0]

When UPnP gives an ipv6 address to the function is_valid_public_ipv4, instead of return False, it throws an error:

Traceback (most recent call last):
  File "lbry/extras/daemon/component.py", line 63, in _setup
  File "lbry/extras/daemon/component.py", line 55, in _setup
  File "lbry/extras/daemon/components.py", line 493, in start
  File "lbry/extras/daemon/components.py", line 430, in _maintain_redirects
  File "lbry/dht/peer.py", line 39, in is_valid_public_ipv4
  File "ipaddress.py", line 79, in ip_network
  File "ipaddress.py", line 2178, in __init__
ValueError: <redacted ipv6>/32 has host bits set

This is because the checks doesn't stop when parsed_ip.version != 4, but CARRIER_GRADE_NAT_SUBNET.supernet_of(ipaddress.ip_network(f"{address}/32")) and IPV4_TO_6_RELAY_SUBNET.supernet_of(ipaddress.ip_network(f"{address}/32"))) needs a valid IPv4 address.

[tzarebczan]

Thanks so much for finding this and opening a PR! Can we show you some appreciation?

[endes0]

Just a small fix, I don't want appreciation. Also, sorry for responding late.