ci: With stable ABI enabled for 3.12+, drop cp313 builds

Author: mborgerson

.github/workflows/build.yml

@@ -43,7 +43,7 @@ jobs:
     runs-on: ${{ matrix.platform.os }}
     strategy:
       matrix:
-        py: [cp310, cp311, cp312, cp313]
+        py: [cp310, cp311, cp312]
         platform:
           - { arch: x86_64,  os: windows-latest,   wheel_tag: win_amd64         }
           - { arch: x86_64,  os: macos-13,         wheel_tag: macosx_x86_64     }