Replace k8s.gcr.io/metrics-server/metrics-server Docker tag with registry.k8s.io/metrics-server/metrics-server #1223

	name: Lint

	on:
	pull_request:
	branches:
	- master

	jobs:
	unit-tests:
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v2
	- name: Determine Go version from go.mod
	run: echo "GO_VERSION=$(grep "go 1." go.mod \| cut -d " " -f 2)" >> $GITHUB_ENV
	- uses: actions/setup-go@v2
	with:
	go-version: ${{ env.GO_VERSION }}
	- uses: actions/cache@v2
	with:
	path: ~/go/pkg/mod
	key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
	restore-keys: \|
	${{ runner.os }}-go-
	- name: Run all linters
	run: make lint

	docs:
	runs-on: ubuntu-latest
	steps:
	- name: Checkout
	uses: actions/checkout@v2
	- name: Generate Chart documentation
	run: make docs
	- name: Check if documentation is on par with Chart changes
	run: git diff --exit-code

	chart-versions:
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v2
	with:
	fetch-depth: '0'
	- name: Verify chart versions have been updated
	run: make lint:versions

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