chore: add Go 1.21 for matrix testing #440

	name: Go

	on:
	push:
	pull_request:

	jobs:
	test:
	name: Unit Tests
	runs-on: ubuntu-latest
	strategy:
	matrix:
	go: [ '1.18.x', '1.19.x', '1.20.x', '1.21.x' ]
	steps:
	- name: Set up Go ${{ matrix.go }}
	uses: actions/setup-go@v4
	with:
	go-version: ${{ matrix.go }}
	id: go

	- name: Check out code into the Go module directory
	uses: actions/checkout@v3

	- name: Get dependencies
	run: \|
	go get -v -t -d ./...

	- name: Lint
	uses: golangci/golangci-lint-action@v3
	with:
	version: v1.51.2

	- name: Test
	run: go test -race -coverprofile=coverage.txt -covermode=atomic ./...

	- name: Codecov
	uses: codecov/codecov-action@v3

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