Fix test suite on Windows to avoid exceeding file handle limit

tests/conftest.py

@@ -0,0 +1,21 @@
+import gc
+import sys
+import pytest
+
+
+@pytest.fixture(autouse=True)
+def gc_after_test():
+    """Run Python's garbage collection after each test on Windows.
+
+    The test suite currently opens many file handles that are not closed until garbage collection
+    runs. This results in flaky test failures on Windows which has a limit of 512 open file handles
+    per process. It could be possible to remove this in the future if the problem is solved upstream
+    (most likely in MIKE IO). See issue below for details:
+
+    https://github.com/DHI/mikecore-python/issues/41
+    """
+    if sys.platform.startswith("win"):
+        yield
+        gc.collect()
+    else:
+        yield