Add cargo check+test for minimal-versions in CI #485

	name: ci
	on: [push, pull_request]
	jobs:
	test:
	name: test
	runs-on: ${{ matrix.os }}
	strategy:
	matrix:
	os: [ubuntu-latest, windows-latest, macOS-latest]
	rust: [1.71, stable, beta, nightly]
	steps:
	- name: Checkout repository
	uses: actions/checkout@v1
	- name: Install Rust
	uses: hecrj/setup-rust-action@v1
	with:
	rust-version: ${{ matrix.rust }}

	# Because of all the features, we run build and test twice -- once with
	# full features and once without any features at all -- to make it more
	# likely that everything works.

	# Clippy.
	#
	# Only do this once with all features enabled.
	- if: matrix.rust != 'beta'
	run: rustup component add clippy
	- if: matrix.rust != 'beta'
	run: cargo clippy --all --all-features -- -D warnings

	# Build
	- run: cargo build --verbose --all --all-features
	- run: cargo build --verbose --all

	# Test
	- run: cargo test --verbose --all --all-features
	- run: cargo test --verbose --all

	# Test using minimal dependency versions from Cargo.toml
	- if: matrix.rust == 'nightly'
	run: \|
	cargo +nightly update -Z minimal-versions
	cargo check --all-features --verbose --all-targets
	cargo test --all-features
	name: Check and test with minimal-versions

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