ci: lower python version to 3.8 in publish-python

This is an attempt to fix the macos has the wrong dylib part of the
issue zxing-cpp#695.

.github/workflows/publish-python.yml

@@ -30,7 +30,9 @@ jobs:
     - name: Set up Python
       uses: actions/setup-python@v5
       with:
-        python-version: '3.12'
+        # set to minimum supported version to make sure macos wheels contain the right binary,
+        # see https://github.com/zxing-cpp/zxing-cpp/issues/695#issuecomment-1951340182
+        python-version: '3.8'
 
     - name: Install cibuildwheel
       run: python3 -m pip install cibuildwheel==2.16.2