Support IPv6 hostnames in dogstatsd

[phil-scale]

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Is your feature request related to a problem? Please describe.

Support IPv6 hostnames in the DogStatsd class so that we can resolve the following issue in IPv6-addressed environments

>>> from datadog.dogstatsd.base import DogStatsd
>>> DogStatsd._get_udp_socket("::", 8126)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/opt/miniconda3/envs/hmi/lib/python3.8/site-packages/datadog/dogstatsd/base.py", line 544, in _get_udp_socket
    sock.connect((host, port))
socket.gaierror: [Errno 8] nodename nor servname provided, or not known

Describe the solution you'd like
Proposed fix: #783

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A clear and concise description of any alternative solutions or features you've considered.

Additional context
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