Merge pull request #2055 from PyCQA/add-315-ci

add python 3.15 to CI

Author: asottile

.github/workflows/main.yml

@@ -30,6 +30,9 @@ jobs:
         - os: ubuntu-latest
           python: '3.14'
           toxenv: py
+        - os: ubuntu-latest
+          python: '3.15-dev'
+          toxenv: py
         # windows
         - os: windows-latest
           python: '3.10'