Update actions/checkout action to v4 #60

	name: CI

	on:
	push:
	branches:
	- master
	pull_request:
	branches:
	- master

	jobs:
	CI:
	runs-on: ubuntu-latest
	strategy:
	matrix:
	toolchain:
	- stable
	- nightly
	steps:
	- name: Checkout
	uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
	- name: Install rust toolchain
	uses: actions-rs/toolchain@v1
	with:
	toolchain: ${{matrix.toolchain}}
	- name: Rustfmt
	uses: actions-rs/cargo@v1
	with:
	command: fmt
	args: -- --check
	- name: Build
	uses: actions-rs/cargo@v1
	with:
	command: build
	- name: Test
	uses: actions-rs/cargo@v1
	with:
	command: test
	- name: Test serde_base64 feature
	uses: actions-rs/cargo@v1
	with:
	command: test
	args: --features serde_base64

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