fixup! Add support for Python 3.13

Author: hugovk

noxfile.py

@@ -28,7 +28,7 @@
 # Black and flake8 clash on the syntax for ignoring flake8's F401 in this file.
 BLACK_EXCLUDES = ["--exclude", "^/google/api_core/operations_v1/__init__.py"]
 
-PYTHON_VERSIONS = ["3.7", "3.8", "3.9", "3.10", "3.11", "3.12"]
+PYTHON_VERSIONS = ["3.7", "3.8", "3.9", "3.10", "3.11", "3.12", "3.13"]
 
 DEFAULT_PYTHON_VERSION = "3.10"
 CURRENT_DIRECTORY = pathlib.Path(__file__).parent.absolute()