chore(deps): update step-security/harden-runner action to v2.21.0

Author: renovate[bot]

.github/workflows/tests.yml

@@ -26,7 +26,7 @@ jobs:
       contents: read
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@b09bb98e06d4d774595224525879c09bc6e98c40 # v2.20.1
+        uses: step-security/harden-runner@05e31511f85b41b11d1cf0ef85d0992719546e2c # v2.21.0
         with:
           egress-policy: audit