Add contents read permission for release chart

[i-am-SR]

Issue #, if available:

Description of changes:
Add contents read permission for release chart

The release chart workflow failed: https://github.com/aws/secrets-store-csi-driver-provider-aws/actions/runs/21648520700

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 61.56%. Comparing base (479590a) to head (72f2533).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #564   +/-   ##
=======================================
  Coverage   61.56%   61.56%           
=======================================
  Files          11       11           
  Lines         752      752           
=======================================
  Hits          463      463           
  Misses        274      274           
  Partials       15       15           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.