Add missing <cstdio> includes #288

	name: PlatformIO Bluepill Environment

	on:
	push:
	branches:
	- "*"
	pull_request:
	branches:
	- "*"

	jobs:
	build:

	runs-on: ubuntu-20.04

	steps:
	- uses: actions/checkout@v2
	with:
	submodules: true

	- name: Set up Python
	uses: actions/setup-python@v1
	- name: Install dependencies
	run: \|
	python -m pip install --upgrade pip
	pip install platformio
	- name: Run PlatformIO for Bluepill
	run: platformio run -d ${{ github.workspace }}/c6021light

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