Merge pull request #698 from ruby/dependabot/github_actions/step-security/harden-runner-2.15.0

Bump step-security/harden-runner from 2.14.2 to 2.15.0

Author: matzbot

.github/workflows/push_gem.yml

@@ -23,7 +23,7 @@ jobs:
 
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@5ef0c079ce82195b2a36a210272d6b661572d83e # v2.14.2
+        uses: step-security/harden-runner@a90bcbc6539c36a85cdfeb73f7e2f433735f215b # v2.15.0
         with:
           egress-policy: audit