* Cache verification info for reuse
* updated hashing
* tried fixing concurrent verification issue
* Added singleflight to avoid concurrent verification
* resolved linter
* Ok I tried something new for a much simpler detector
* some enhancements
* Added test case
* re-added tags
* Deduplicate concurrent credential verification requests via singleflight
* Enforce dedup key via DoWithDedup, remove public WithDedupKey
* remove unused func
* Remove dead io.Copy after io.ReadAll error in singleflight transport
* Preserve deadline on shared singleflight request after WithoutCancel
* Added test cases and moved existing ones to http_test.go
* fixed linter