TST: Adapt Ert mode test to Ert 14

Ert 14.0.0 deprecated 'iterative ensemble smoother' mode. While this
mode should also be removed from the Ert mode enum, we cannot do so
safely within pinning the Ert version above 14. We cannot do that until
we stop supporting Python 3.8.

src/fmu/dataio/_models/fmu_results/enums.py

@@ -71,6 +71,8 @@ class ErtSimulationMode(str, Enum):
     ensemble_smoother = "ensemble_smoother"
     es_mda = "es_mda"
     evaluate_ensemble = "evaluate_ensemble"
+    # TODO: Remove 'iterative_ensemble_smoother' when Python 3.8 deprecated. It was
+    # removed # with Ert 14.0.0.
     iterative_ensemble_smoother = "iterative_ensemble_smoother"
     manual_update = "manual_update"
     test_run = "test_run"

tests/test_units/test_fmuprovider_class.py

@@ -411,8 +411,13 @@ def test_fmuprovider_workflow_reference(fmurun_w_casemetadata, globalconfig2):
 def test_ert_simulation_modes_one_to_one() -> None:
     """Ensure dataio known modes match those defined by Ert.
 
-    These are currently defined in `ert.mode_definitions`. `MODULE_MODE` is skipped due
-    to seemingly being relevant to Ert internally -- the modes are duplicated there."""
+    These are currently defined in `ert.mode_definitions`.
+
+    - `MODULE_MODE` is skipped due to seemingly being relevant to Ert internally.
+      The modes are duplicated there.
+    - `iterative_ensemble_mode` was removed in Ert 14. It must be ignored here for as
+      long as we support Python 3.8.
+    """
     ert_mode_definitions = importlib.import_module("ert.mode_definitions")
     ert_modes = {
         getattr(ert_mode_definitions, name)
@@ -422,4 +427,10 @@ def test_ert_simulation_modes_one_to_one() -> None:
         and isinstance(getattr(ert_mode_definitions, name), str)
     }
     dataio_known_modes = {mode.value for mode in ErtSimulationMode}
+
+    # TODO: Remove this check when Python 3.8 deprecated.
+    ert_version = importlib.metadata.version("ert")
+    if int(ert_version.split(".")[0]) >= 14:
+        dataio_known_modes.discard("iterative_ensemble_smoother")
+
     assert ert_modes == dataio_known_modes