Add RETICULATE_PYTHON env var, close #72 #4

	name: mamba-py

	on:
	schedule:
	- cron: '0 21 * * 6'
	push:
	branches:
	- 'master'
	- 'main'

	jobs:
	docker:
	runs-on: ubuntu-20.04
	steps:
	-
	name: Checkout
	uses: actions/checkout@v2
	-
	name: Docker meta
	id: meta
	uses: docker/metadata-action@v3
	with:
	# list of Docker images to use as base name for tags
	images: \|
	geocompr/geocompr
	ghcr.io/geocompx/docker
	# generate Docker tags based on the following events/attributes
	tags: \|
	type=raw,value=mamba-py
	type=sha,prefix=mamba_
	type=schedule,pattern={{date 'YYYY-MM-DD'}},prefix=mamba_
	-
	name: Set up QEMU
	uses: docker/setup-qemu-action@v1
	-
	name: Set up Docker Buildx
	uses: docker/setup-buildx-action@v1
	-
	name: Login to DockerHub
	uses: docker/login-action@v1
	with:
	username: ${{ secrets.DOCKERHUB_USERNAME }}
	password: ${{ secrets.DOCKERHUB_TOKEN }}
	-
	name: Login to GitHub Container Registry
	uses: docker/login-action@v1
	with:
	registry: ghcr.io
	username: ${{ github.repository_owner }}
	password: ${{ secrets.GITHUB_TOKEN }}
	-
	name: Build and push
	uses: docker/build-push-action@v2
	with:
	context: mamba-py
	push: ${{ github.event_name != 'pull_request' }}
	tags: ${{ steps.meta.outputs.tags }}
	labels: ${{ steps.meta.outputs.labels }}

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