Upgrade to actions/setup-go@v5, improve README #11

	name: Bechmark

	on:
	pull_request:

	jobs:
	benchmark:
	name: Benchmark
	runs-on: ubuntu-latest
	steps:
	- name: Set up Go
	uses: actions/setup-go@v5
	with:
	go-version: ^1.17

	- name: Git clone (master)
	uses: actions/checkout@v4
	with:
	ref: master

	- name: Run benchmark (master)
	run: go test -bench=. -count=10 -benchmem \| tee /tmp/master.txt

	- name: Git clone (PR)
	uses: actions/checkout@v4

	- name: Run benchmark (PR)
	run: go test -bench=. -count=10 -benchmem \| tee /tmp/pr.txt

	- name: Install benchstat
	run: go install golang.org/x/perf/cmd/benchstat@latest

	- name: Run benchstat
	run: cd /tmp && benchstat master.txt pr.txt \| tee /tmp/result.txt

	- name: Comment on PR with benchmark results
	uses: actions/github-script@v6
	with:
	script: \|
	const fs = require('fs');
	const results = fs.readFileSync('/tmp/result.txt', 'utf8');
	const issue_number = context.payload.pull_request.number;
	const { owner, repo } = context.repo;

	await github.rest.issues.createComment({
	owner,
	repo,
	issue_number,
	body: `### Benchmark Results\n\n\`\`\`\n${results}\n\`\`\``
	});

Provide feedback