Pin actions

Author: osalmi

.github/workflows/tests.yml

@@ -27,7 +27,7 @@ jobs:
         working-directory: tests
 
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
 
       - uses: ./
         with: