Update pyproject.toml with Python 3.14 support and removed 3.9 support

per GoogleCloudPlatform#1339

Author: graingert-coef

pyproject.toml

@@ -33,11 +33,11 @@ classifiers = [
     "Intended Audience :: Developers",
     "Programming Language :: Python",
     "Programming Language :: Python :: 3",
-    "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
     "Programming Language :: Python :: 3.13",
+    "Programming Language :: Python :: 3.14",
     "Operating System :: OS Independent",
 ]
 dependencies = [