Move var substitute to constext. #3

	name: IaC Diff

	on:
	push:
	branches:
	- '*'

	jobs:
	deploy:
	name: Deploy CDK stacks to test
	runs-on: ubuntu-latest
	permissions:
	actions: write
	contents: read
	id-token: write
	env:
	DEPLOY_ROLE: ${{vars.GHA_AWS_DEPLOY_ROLE}}
	steps:
	-
	name: Configure AWS credentials
	uses: aws-actions/configure-aws-credentials@v1
	with:
	role-to-assume: $DEPLOY_ROLE
	aws-region: eu-west-2
	-
	name: Checkout repo
	uses: actions/checkout@v2
	-
	name: Install dependencies
	run: cd iac/ && npm install
	-
	name: CDK synth
	run: cd iac/ && cdk diff

Provide feedback