added `testthat` as an explicit dependency #31

	name: build_R
	# build for R, skip scala tests and python build
	on:
	push:
	branches:
	- 'r/**'
	- 'R/**'

	jobs:
	build:
	runs-on: ubuntu-20.04
	env:
	GITHUB_PAT: ${{ secrets.GITHUB_TOKEN }}
	strategy:
	matrix:
	python: [ 3.9.5 ]
	numpy: [ 1.21.5 ]
	gdal: [ 3.4.3 ]
	spark: [ 3.3.2 ]
	R: [ 4.1.2 ]
	steps:
	- name: checkout code
	uses: actions/checkout@v2
	- name: build scala with skipping tests
	uses: ./.github/actions/scala_build
	with:
	skip_tests: 'true'
	- name: build r artefacts
	uses: ./.github/actions/r_build
	- name: upload artefacts
	uses: ./.github/actions/upload_artefacts

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