release.sh: build directly to per-platform name

Avoids a collision on case-insensitive filesystems (macOS default)
where the uppercase KCL file in the repo root clashes with `go build
-o kcl`. Also produces kcl_windows_amd64.exe.gz so Windows users get
a runnable .exe after unzip.

Merge pull request #50 from twmb/updates

bump deps, fix raw-req

Merge pull request #47 from twmb/changelog

changelog: note 0.16.0

Merge pull request #39 from twmb/deps

update deps

Merge pull request #37 from twmb/k3.6

support --as-version 3.6

kcl: fix `admin topic create --config-path`, bump deps, note release

bump deps for v0.11.0

Merge pull request #27 from twmb/kafka_34

Kafka 34

CHANGELOG: missing paren

kcl: bump deps