Bump pytest-homeassistant-custom-component from 0.12.15 to 0.12.20

Bumps [pytest-homeassistant-custom-component](https://github.com/MatthewFlamm/pytest-homeassistant-custom-component) from 0.12.15 to 0.12.20.
- [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@0.12.15...0.12.20)

---
updated-dependencies:
- dependency-name: pytest-homeassistant-custom-component
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

requirements_test.txt

@@ -1,2 +1,2 @@
 -r requirements_dev.txt
-pytest-homeassistant-custom-component==0.12.15
+pytest-homeassistant-custom-component==0.12.20