Drop `mutex_m` dependency #106

	name: test on CI
	on:
	push:
	branches: [master]
	pull_request:
	jobs:
	test:
	runs-on: ubuntu-latest
	strategy:
	matrix:
	ruby:
	[
	"2.3",
	"2.4",
	"2.5",
	"2.6",
	"2.7",
	"3.0",
	"3.1",
	"3.2",
	"3.3",
	"head",
	]
	steps:
	- uses: actions/checkout@v4
	- name: Set up Ruby
	uses: ruby/setup-ruby@v1
	with:
	ruby-version: ${{ matrix.ruby }}
	bundler-cache: true
	- name: Run tests
	run: bundle exec rake test:units

	test-legacy:
	runs-on: ubuntu-20.04
	strategy:
	matrix:
	ruby: ["2.0", "2.1", "2.2"]
	steps:
	- uses: actions/checkout@v4
	- name: Set up Ruby
	uses: ruby/setup-ruby@v1
	with:
	ruby-version: ${{ matrix.ruby }}
	bundler-cache: true
	- name: Run tests
	run: bundle exec rake test:units

	test-all:
	runs-on: ubuntu-latest
	needs: [test, test-legacy]
	if: always()
	steps:
	- name: All tests ok
	if: ${{ !(contains(needs.*.result, 'failure')) }}
	run: exit 0
	- name: Some tests failed
	if: ${{ contains(needs.*.result, 'failure') }}
	run: exit 1

	rubocop:
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v4
	- name: Set up Ruby
	uses: ruby/setup-ruby@v1
	with:
	ruby-version: "2.7"
	bundler-cache: true
	- name: Run rubocop
	run: bundle exec rake lint

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