Include Python 3.13 in github actions (#554)

* Include Python 3.13 in github actions list
* Include version in supported versions list

Author: dbieber

.github/workflows/build.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-20.04
     strategy:
       matrix:
-        python-version: ["3.7", "3.8", "3.9", "3.10", "3.11", "3.12"]
+        python-version: ["3.7", "3.8", "3.9", "3.10", "3.11", "3.12", "3.13.0-rc.2"]
 
     steps:
      # Checkout the repo.

setup.py

@@ -67,6 +67,7 @@
         'Programming Language :: Python :: 3.10',
         'Programming Language :: Python :: 3.11',
         'Programming Language :: Python :: 3.12',
+        'Programming Language :: Python :: 3.13',
 
         'Operating System :: OS Independent',
         'Operating System :: POSIX',