docs: update v4 migration guide for metrics #3352

	# This action requires that any PR targeting the main branch should touch at
	# least one CHANGELOG file. If a CHANGELOG entry is not required, add the "skip-changelog"
	# label to disable this action.

	name: changelog

	on:
	pull_request:
	types: [opened, synchronize, reopened, labeled, unlabeled]
	branches:
	- main
	jobs:
	changelog:
	runs-on: ubuntu-latest
	if: "!contains(github.event.pull_request.labels.*.name, 'skip-changelog')"
	env:
	TOWNCRIER_VERSION: 22.12.0
	PR_NUMBER: ${{ github.event.number }}
	steps:
	- uses: actions/checkout@v4
	with:
	fetch-depth: 50
	- name: Add PR base ref
	run: \|
	git fetch origin ${{ github.base_ref }} --depth=50
	- name: install towncrier
	run: pip install towncrier==${{ env.TOWNCRIER_VERSION }}
	- name: Check if new CHANGELOG entries added
	run: \|
	make check-changelog
	- name: Check if new CHANGELOG entries reference the correct PR
	run: \|
	git diff --name-only origin/${{ github.base_ref }} HEAD .changelog \| grep ${PR_NUMBER}

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