Add 3.13 to CI and trove classifiers.

Author: vsajip

.github/workflows/tests.yml

@@ -33,7 +33,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, macos-12, macos-latest, windows-latest]
-        python-version: ['3.7', '3.8', '3.9', '3.10', '3.11', '3.12', 'pypy-3.9']
+        python-version: ['3.7', '3.8', '3.9', '3.10', '3.11', '3.12', '3.13', 'pypy-3.9']
         exclude:
           # macos-latest does not have Python 3.7
           - os: macos-latest

setup.cfg

@@ -38,6 +38,7 @@ classifiers =
     Programming Language :: Python :: 3.10
     Programming Language :: Python :: 3.11
     Programming Language :: Python :: 3.12
+    Programming Language :: Python :: 3.13
     Operating System :: OS Independent
     Topic :: Software Development :: Libraries :: Python Modules"
 project_urls =