Ensure tests are run

tests/__init__.py

@@ -162,6 +162,7 @@ def self_test_suite() -> unittest.TestSuite:
         "mbox",
         "merge",
         "merge_drivers",
+        "midx",
         "missing_obj_finder",
         "notes",
         "objects",

tests/compat/__init__.py

@@ -34,6 +34,7 @@ def test_suite() -> unittest.TestSuite:
         "dumb",
         "index",
         "lfs",
+        "midx",
         "pack",
         "patch",
         "porcelain",