adds RegisterCustom function to tag package #349

	name: bench_pr
	on: [pull_request]
	jobs:
	build:
	name: Benchmark (PR)
	runs-on: ubuntu-latest
	env:
	GOBIN: /home/runner/go
	steps:
	- name: Set up Go 1.18
	uses: actions/setup-go@v3
	with:
	go-version: 1.18
	id: go

	- name: Check out code
	uses: actions/checkout@v1

	- name: Get dependencies
	run: \|
	go mod download

	- name: Benchmark against GITHUB_BASE_REF
	run: \|
	go install golang.org/x/perf/cmd/benchstat@latest
	echo "New Commit:"
	git log -1 --format="%H"
	go test -bench=. -benchmem -benchtime=10x -count=7 > $HOME/new.txt
	git reset --hard HEAD
	git checkout $GITHUB_BASE_REF
	echo "Base Commit:"
	git log -1 --format="%H"
	go test -bench=. -benchmem -benchtime=10x -count=7 > $HOME/old.txt
	$GOBIN/benchstat $HOME/old.txt $HOME/new.txt

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