build: 🔧 specify Python 3.12 in CI setup

Updated CI workflow to explicitly use Python 3.12 for improved consistency and reproducibility of builds.

.github/workflows/ci.yml

@@ -22,6 +22,7 @@ jobs:
       - name: Setup Python
         uses: astral-sh/setup-uv@v2
         with:
+          version: 3.12
           enable-cache: true
       - name: Run
         run: |