Bump actions/checkout from 5 to 6 (#27)

Author: dependabot[bot]

.github/workflows/build.yml

@@ -20,7 +20,7 @@ jobs:
     steps:
       # Checks-out your repository under $GITHUB_WORKSPACE
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Setup caching for tectonic
         uses: actions/cache@v4