Update build.yml

Author: LiamConnors

.github/workflows/build.yml

@@ -22,7 +22,7 @@ jobs:
       - name: Install uv
         uses: astral-sh/setup-uv@v5
         with:
-          python-version: '3.x'
+          python-version: '3.12'
 
       - name: Install Python dependencies
         run: uv pip install --system PyYAML==6.0.1 python-frontmatter==0.5.0