Harden GitHub Action references

Author: kvz

.github/workflows/tests.yml

@@ -26,18 +26,18 @@ jobs:
 
       steps:
       - name: Checkout Repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Set up JDK
-        uses: actions/setup-java@v2
+        uses: actions/setup-java@v5
         with:
           java-version: ${{ matrix.java }}
           distribution: 'adopt'
 
       # This allows us to test Smart CDN Signatures against the Node SDK reference
       # implementation for parity.
       - name: Set up Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v6
         with:
           node-version: 24
 
@@ -52,7 +52,7 @@ jobs:
 
       - name: Upload coverage to Codecov
         if: matrix.java == '11'
-        uses: codecov/codecov-action@v5
+        uses: codecov/codecov-action@fb8b3582c8e4def4969c97caa2f19720cb33a72f # v6.0.2
         env:
           CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}