Merge pull request #68 from ruby/dependabot/github_actions/step-security/harden-runner-2.21.0

Bump step-security/harden-runner from 2.20.0 to 2.21.0

Author: hsbt

.github/workflows/push_gem.yml

@@ -25,7 +25,7 @@ jobs:
 
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
+        uses: step-security/harden-runner@05e31511f85b41b11d1cf0ef85d0992719546e2c # v2.21.0
         with:
           egress-policy: audit