SECENG-364] Pin GitHub Actions to commit SHAs (#16)

Author: sginovker

.github/workflows/test.yml

@@ -8,7 +8,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@master
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
 
       - name: Set up Ruby
         uses: ruby/setup-ruby@4c56a21280b36d862b5fc31348f463d60bdc55d5 # v1.301.0