The old Command::cargo_bin() is deprecated and will break when Cargo
changes build directory layout. Updated to use cargo_bin!() macro instead.
Bumped assert_cmd to 2.0.16 to get the new macro.
Fixes#3528
There is now a new stage in the CICD workflow present, which will build
`bat` with the `BAT_SYSTEM_CONFIG_PREFIX` set to load the config file
from `/tests/examples/system_config/bat/config`, plus a basic set of
tests, to ensure the feature is working as expected. By default the
tests are set to ignored, as they need special setup before they can be
run.
