tools: pin actions by hash for tools.yml

Signed-off-by: Gabriela Gutierrez <[email protected]>

Author: gabibguti

.github/workflows/tools.yml

@@ -165,7 +165,7 @@ jobs:
                 ./tools/update-nghttp2.sh "$NEW_VERSION"
               fi
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@ac593985615ec2ede58e132d2e21d2b1cbd6127c # v3.3.0
         with:
           persist-credentials: false
       - run: ${{ matrix.run }}