ci: pin action by commit hash

Author: andreynering

.github/workflows/test.yml

@@ -19,7 +19,7 @@ jobs:
     runs-on: ${{matrix.platform}}
     steps:
       - name: Check out code
-        uses: actions/checkout@v6
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
 
       - name: Set up Go ${{matrix.go-version}}
         uses: actions/setup-go@4a3601121dd01d1626a1e23e37211e3254c1c06c # v6.4.0