Bump step-security/harden-runner from 2.19.0 to 2.19.4

Bumps [step-security/harden-runner](https://github.com/step-security/harden-runner) from 2.19.0 to 2.19.4.
- [Release notes](https://github.com/step-security/harden-runner/releases)
- [Commits](step-security/harden-runner@8d3c67d...9af89fc)

---
updated-dependencies:
- dependency-name: step-security/harden-runner
  dependency-version: 2.19.4
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/release_gem.yml

@@ -18,7 +18,7 @@ jobs:
 
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@8d3c67de8e2fe68ef647c8db1e6a09f647780f40 # v2.19.0
+        uses: step-security/harden-runner@9af89fc71515a100421586dfdb3dc9c984fbf411 # v2.19.4
         with:
           egress-policy: audit