Update pytest-homeassistant-custom-component requirement

Updates the requirements on [pytest-homeassistant-custom-component](https://github.com/MatthewFlamm/pytest-homeassistant-custom-component) to permit the latest version.
- [Release notes](https://github.com/MatthewFlamm/pytest-homeassistant-custom-component/releases)
- [Changelog](https://github.com/MatthewFlamm/pytest-homeassistant-custom-component/blob/master/CHANGELOG.md)
- [Commits](MatthewFlamm/pytest-homeassistant-custom-component@0.2.0...0.3.0)

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

requirements-test.txt

@@ -6,4 +6,4 @@ pylint~=2.7
 pylint-strict-informational==0.1
 pytest~=6.2
 pytest-cov~=2.10
-pytest-homeassistant-custom-component~=0.2
+pytest-homeassistant-custom-component~=0.3