fix: use sha384-prefixed signatures for list requests

[tim-kos]

Summary

• update listRequest() to sign with HMAC-SHA384 (instead of SHA1)
• prefix list signatures with sha384: to match the rest of the SDK and modern auth-key defaults
• add regression coverage in TestListRequest_UsesSha384PrefixedSignature

Validation

• go test ./... (fails in this local environment with a dyld toolchain error: missing LC_UUID load command)

Closes transloadit/api2#5337

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.60%. Comparing base (f2fda53) to head (5097904).

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #43      +/-   ##
==========================================
+ Coverage   81.09%   82.60%   +1.50%     
==========================================
  Files           6        6              
  Lines         455      345     -110     
==========================================
- Hits          369      285      -84     
+ Misses         58       32      -26     
  Partials       28       28              

☔ 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.