ci: pin GitHub Actions to commit SHAs

Author: maxencerb

.github/workflows/test.yml

@@ -16,13 +16,13 @@ jobs:
     name: Foundry project
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@fbc6f3992d24b796d5a048ff273f7fcc4a7b6c09 # v5
         with:
           persist-credentials: false
           submodules: recursive
 
       - name: Install Foundry
-        uses: foundry-rs/foundry-toolchain@v1.6.0
+        uses: foundry-rs/foundry-toolchain@8b0419c685ef46cb79ec93fbdc131174afceb730 # v1.6.0
 
       - name: Show Forge version
         run: forge --version