Update datadog to 0.22.0

[pyup-bot]

This PR updates datadog from 0.20.0 to 0.22.0.

Changelog

0.22.0

**New API endpoint: https://api.datadoghq.com/api**

The Datadog API client now uses https://api.datadoghq.com/api endpoint instead of https://app.datadoghq.com/api.
See [257][] for more details.

* [BUGFIX] API: Close requests' sessions to limit memory usage, [272][] (thanks [thehesiod][])
* [BUGFIX] Dogwrap: Fix `TypeError` exceptions when truncating `stdout`, `stderr` with Python 3, [260][], [267][] (thanks [cabouffard][], [glasnt][])
* [FEATURE] DogStatsD: Add client level tags to status checks, [279][] (thanks [marshallbrekka][])
* [FEATURE] DogStatsD: Add support for `statsd_socket_path` option in `initialize` function, [282][]
* [IMPROVEMENT] Dogwrap: Default output encoding to UTF-8, [268][] (thanks [glasnt][])

0.21.0

**Search hosts: `Infrastructure.search` is deprecated**
The `Infrastructure.search` method is deprecated in favor of the new `Hosts.search` method.

* [BUGFIX] API: Prevent exception contexts from logging URLs and credentials, [266][]
* [FEATURE] API: Add `search` and `totals` methods to the `Hosts` resource, [261][]

Links

• PyPI: https://pypi.org/project/datadog
• Changelog: https://pyup.io/changelogs/datadog/
• Homepage: https://www.datadoghq.com