Drop Python 3.8/3.9 support, add 3.13/3.14 classifiers

Align python_requires and classifiers with CI matrix which tests
3.10-3.14. Requested by requests 2.33.0 dropping Python 3.9.

Closes #839

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: mitchh456

setup.py

@@ -48,7 +48,7 @@
     author_email="support@scoutapm.com",
     license="MIT",
     zip_safe=False,
-    python_requires=">=3.8, <4",
+    python_requires=">=3.10, <4",
     packages=packages,
     package_dir={str(""): str("src")},
     ext_modules=ext_modules,
@@ -80,10 +80,10 @@
         "Operating System :: MacOS",
         "Operating System :: POSIX",
         "Operating System :: POSIX :: Linux",
-        "Programming Language :: Python :: 3.8",
-        "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",
     ],
 )