Update ovos-core requirement in /requirements

Updates the requirements on [ovos-core](https://github.com/OpenVoiceOS/ovos-core) to permit the latest version.
- [Release notes](https://github.com/OpenVoiceOS/ovos-core/releases)
- [Changelog](https://github.com/OpenVoiceOS/ovos-core/blob/dev/CHANGELOG.md)
- [Commits](OpenVoiceOS/ovos-core@V0.0.8a50...2.2.0a1)

---
updated-dependencies:
- dependency-name: ovos-core
  dependency-version: 2.1.6a1
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements/test.txt

@@ -1,4 +1,4 @@
-ovos-core>=0.0.8a50
+ovos-core>=2.2.0a1
 ovoscope>=0.1.0
 ovos-adapt-parser>=1.3.1a1
 pytest