.github: add building and testing workflows #5

	name: Build

	on:
	pull_request:
	branches:
	- master
	types: [opened, synchronize]
	paths-ignore:
	- '*/.md'
	push:
	# Build for the master branch.
	branches:
	- master
	workflow_dispatch:
	inputs:
	ref:
	description: 'Ref to build Bench, GoNode and SharpNode images [default: latest master; examples: 0a4ff9d3e4a9ab432fd5812eb18c98e03b5a7432]'
	required: false
	default: ''

	jobs:
	build_image:
	name: Build Bench, GoNode and SharpNode docker images
	runs-on: ubuntu-20.04

	steps:
	- uses: actions/checkout@v3
	with:
	ref: ${{ github.event.inputs.ref }}
	fetch-depth: 0

	- uses: docker/setup-buildx-action@v3
	- uses: docker/build-push-action@v5
	with:
	context: .
	cache-from: type=gha
	cache-to: type=gha,mode=max

	- name: Build
	run: make build

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