fix: upgrade cloudevents to latest if on go1.18 or later #625

	name: Go Unit CI
	on:
	push:
	branches:
	- main
	pull_request:
	permissions:
	contents: read

	jobs:
	test:
	runs-on: ${{ matrix.os }}
	strategy:
	matrix:
	go: ['1.18', '1.19', '1.20', '1.21']
	os: [ubuntu-latest, macos-latest, windows-latest]
	steps:
	- name: Harden Runner
	uses: step-security/harden-runner@f086349bfa2bd1361f7909c78558e816508cdc10 # v2.8.0
	with:
	disable-sudo: true
	egress-policy: block
	allowed-endpoints: >
	api.github.com:443
	github.com:443
	objects.githubusercontent.com:443
	proxy.golang.org:443

	- name: Checkout code
	uses: actions/checkout@a5ac7e51b41094c92402da3b24376905380afc29 # v4.1.6
	- name: Setup Go
	uses: actions/setup-go@cdcb36043654635271a94b9a6d1392de5bb323a7 # v5.0.1
	with:
	go-version: ${{ matrix.go }}
	check-latest: true
	- name: Build and test
	run: "go test ./..."
	- name: Vet
	run: "go vet ./..."

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