Bump step-security/harden-runner from 2.2.1 to 2.8.1

Bumps [step-security/harden-runner](https://github.com/step-security/harden-runner) from 2.2.1 to 2.8.1.
- [Release notes](https://github.com/step-security/harden-runner/releases)
- [Commits](step-security/harden-runner@1f99358...17d0e2b)

---
updated-dependencies:
- dependency-name: step-security/harden-runner
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/testing.yml

@@ -32,7 +32,7 @@ jobs:
         go: [ "1.15", "1.16", "1.17", "1.18", "1.19", "1.20" ]
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@1f99358870fe1c846a3ccba386cc2b2246836776 # v2.2.1
+        uses: step-security/harden-runner@17d0e2bd7d51742c71671bd19fa12bdc9d40a3d6 # v2.8.1
         with:
           egress-policy: audit
           disable-telemetry: true