a local port allows "" or 0. use ephemeral port. #224

	name: Go
	on: [push, pull_request]
	jobs:
	test:
	strategy:
	matrix:
	go:
	- "1.20"
	- "1.21"
	name: Build
	runs-on: ubuntu-latest
	steps:
	- name: Set up Go
	uses: actions/setup-go@v5
	with:
	go-version: ${{ matrix.go }}
	id: go

	- name: Check out code into the Go module directory
	uses: actions/checkout@v4

	- name: Build & Test
	run: \|
	go test -race -v ./...
	env:
	TZ: Asia/Tokyo # for time.Local

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