`go run golang.org/x/tools/gopls/internal/analysis/modernize/cmd/modernize@latest -fix -test ./...` executed.
`go generate ./...` ran afterwards to keep generated.
* Refactor streaming signatureV4 w/ state machine
- Used state machine to make transitions between reading chunk header,
chunk data and trailer explicit.
* debug: add print/panic statements to gather more info on CI failure
* Persist lastChunk status between Read() on ChunkReader
... remove panic() which was added as interim aid for debugging.
* Add unit-tests to cover v4 streaming signature
