[CI] Bump step-security/harden-runner from 2.5.1 to 2.6.0 (#449)

Bumps [step-security/harden-runner](https://github.com/step-security/harden-runner) from 2.5.1 to 2.6.0.
- [Release notes](https://github.com/step-security/harden-runner/releases)
- [Commits](step-security/harden-runner@8ca2b8b...1b05615)

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

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Author: dependabot[bot]

.github/workflows/dependency-review.yml

@@ -17,7 +17,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@8ca2b8b2ece13480cda6dacd3511b49857a23c09 # v2.5.1
+        uses: step-security/harden-runner@1b05615854632b887b69ae1be8cbefe72d3ae423 # v2.6.0
         with:
           egress-policy: audit