Update pinned Python version

Author: mtkennerly

.github/workflows/main.yaml

@@ -32,6 +32,8 @@ jobs:
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/setup-python@v5
+        with:
+          python-version: '3.10'
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0