update target python versions (#38)

Author: asottile-sentry

.github/workflows/main.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python: ['3.7', '3.8', '3.9', '3.10', '3.11', '3.12']
+        python: ['3.8', '3.9', '3.10', '3.11', '3.12', '3.13']
     steps:
     - uses: actions/checkout@v3
     - uses: actions/setup-python@v4