Unable to find group name outside of BP1 resources

[rt17603]

Describe the bug

Observation tests which call acrg.read.utils.obs_database() via acrg.read.obs.get_obs() function fail within the CI due to getgrnam() not being able to find "acrg" group.

=========================== short test summary info ============================
FAILED tests/test_obs.py::test_get_obs_site - KeyError: "getgrnam(): name not...
FAILED tests/test_obs.py::test_get_obs_variability - KeyError: "getgrnam(): n...
FAILED tests/test_obs.py::test_get_obs_gosat - KeyError: "getgrnam(): name no...
===== 3 failed, 215 passed, 38 skipped, 1830 warnings in 462.14s (0:07:42) =====

To Reproduce
Create a PR to run the tests via the CI. This will produce the error.

Expected behavior
Expect tests to pass

Additional context
These tests will pass when running on the BP1 system (or any system with an "acrg" group)