chore: test the new StatusStr vs severity_map

Author: dimaqq

tests/validate/test_status_severity.py

@@ -0,0 +1,10 @@
+from juju.status import StatusStr, severity_map
+
+
+def test_status_str_values():
+    for name, value in StatusStr._member_map_.items():
+        assert name == value
+
+
+def test_severity_map():
+    assert set(StatusStr._member_names_) == set(severity_map)