chore(deps): upgrade RestSharp, use builtin support for synchronous requests

[bednar]

Proposed Changes

1. Updated RestSharp to 108.0.2
2. Use builtin support for synchronous HTTP requests from RestSharp

Checklist

• CHANGELOG.md updated
• Rebased/mergeable
• dotnet test completes successfully
• Commit messages are conventional
• Sign CLA (if not already signed)

[codecov-commenter]

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.52%. Comparing base (83fc2da) to head (28dad07).
Report is 208 commits behind head on master.

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #368   +/-   ##
=======================================
  Coverage   87.52%   87.52%           
=======================================
  Files          76       76           
  Lines        6638     6638           
=======================================
  Hits         5810     5810           
  Misses        828      828           

☔ 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.