Code review comment for ~xavpaice/charm-grafana:fix_unit_tests_ci

This test checks the get_installed_package_version function. The test runs "apt list --installed" and the tested function uses "apt-cache policy" and looks for the "Installed: <version>" line.

Since both tox and python3 are installed via apt (to run jobs in jenkins), I think this test looks good.

Thanks.