Allow cold startup in subprocess compatibility checks

Author: Kludex

tests/client/test_package.py

@@ -135,6 +135,7 @@ def test_full_sdk_imports_preserve_module_attributes_and_exception_names(first_i
         text=True,
         encoding="utf-8",
         check=False,
-        timeout=5,
+        # Cold interpreter imports include coverage startup under xdist.
+        timeout=20,
     )
     assert result.returncode == 0, result.stderr