feat(datastore): update noxfile.py to use dynamic MYPY_CONFIG_FILE

Author: chalmerlowe

packages/google-cloud-datastore/noxfile.py

@@ -46,6 +46,8 @@
 PREVIEW_PYTHON_VERSION = "3.14"
 
 CURRENT_DIRECTORY = pathlib.Path(__file__).parent.absolute()
+# Path to the centralized mypy configuration file at the repository root.
+MYPY_CONFIG_FILE = str(CURRENT_DIRECTORY.parent.parent / "mypy.ini")
 
 if (CURRENT_DIRECTORY / "testing").exists():
     LOWER_BOUND_CONSTRAINTS_FILE = (
@@ -107,7 +109,7 @@ def mypy(session):
     session.install(".")
     session.run(
         "mypy",
-        "--config-file=../../mypy.ini",
+        f"--config-file={MYPY_CONFIG_FILE}",
         "-p",
         "google",
         # TODO(https://github.com/googleapis/google-cloud-python/issues/16083)