Attempt to fix mypy error

Author: shadeMe

thinc/tests/regression/issue519/test_issue519.py

@@ -1,4 +1,5 @@
 import subprocess
+
 try:
     import importlib.resources as importlib_resources
 except ImportError:
@@ -16,10 +17,12 @@ def test_issue519():
     This test can take up to 45 seconds, and is thus marked as slow.
     """
     # Determine the name of the parent module (which contains the test program)
-    parent_module_name = __name__[:__name__.rfind(".")]
+    parent_module_name = __name__[: __name__.rfind(".")]
 
     # Load test program that calls a Thinc API with variadic arguments
     program_text = importlib_resources.read_text(parent_module_name, "program.py")
 
     # Ask Mypy to type-check the loaded program text
-    subprocess.run(["mypy", "--command", program_text], check=True)
+    subprocess.run(
+        ["mypy", "--command", program_text, "--package", "thinc"], check=True
+    )