fix: update default solver version to release-25.9 (#1924)

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: benflexcompute

flow360/version.py

@@ -3,4 +3,4 @@
 """
 
 __version__ = "25.9.5"
-__solver_version__ = "release-25.8"
+__solver_version__ = "release-25.9"

tests/simulation/test_updater.py

@@ -18,7 +18,7 @@
 from flow360.component.simulation.framework.updater_utils import Flow360Version
 from flow360.component.simulation.services import ValidationCalledBy, validate_model
 from flow360.component.simulation.validation.validation_context import ALL
-from flow360.version import __version__
+from flow360.version import __solver_version__, __version__
 
 
 @pytest.fixture(autouse=True)
@@ -44,6 +44,18 @@ def test_version_consistency():
     )
 
 
+def test_default_solver_version_matches_module_version():
+    """For non-beta releases (vA.B.C), the default solver version must be 'release-A.B'."""
+    version = Flow360Version(__version__)
+    if re.search(r"b\d+$", __version__):
+        pytest.skip("Beta version, skipping solver version check")
+    expected_solver_version = f"release-{version.major}.{version.minor}"
+    assert __solver_version__ == expected_solver_version, (
+        f"Default solver version mismatch: __solver_version__ is '{__solver_version__}', "
+        f"but expected '{expected_solver_version}' based on __version__ '{__version__}'"
+    )
+
+
 def test_version_greater_than_highest_updater_version():
     current_python_version = Flow360Version(__version__)
     assert (