Raise a `GitnotInstalled` exception if `git` is not installed (closes… #276

	name: CI

	on: [ push, pull_request ]

	jobs:
	tests:
	runs-on: ubuntu-latest
	strategy:
	fail-fast: false
	matrix:
	ruby:
	- 2.5
	- 2.6
	- 2.7
	- '3.0'
	- 3.1
	- 3.2
	- jruby
	- truffleruby-head
	name: Ruby ${{ matrix.ruby }}
	steps:
	- uses: actions/checkout@v2
	- name: Set up Ruby
	uses: ruby/setup-ruby@v1
	with:
	ruby-version: ${{ matrix.ruby }}
	- name: Install dependencies
	run: bundle install --jobs 4 --retry 3
	- name: Run tests
	run: bundle exec rake test

	# rubocop linting
	rubocop:
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v2
	- name: Set up Ruby
	uses: ruby/setup-ruby@v1
	with:
	ruby-version: 2.7
	- name: Install dependencies
	run: bundle install --jobs 4 --retry 3
	- name: Run rubocop
	run: bundle exec rubocop --parallel

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