Move CI to Github Actions

Makefile

@@ -1,21 +1,21 @@
 .PHONY: docs
 init:
-	pip install pipenv --upgrade
-	pipenv install --dev
+	pip install -e .[socks]
+	pip install -r requirements-dev.txt
 test:
 	# This runs all of the tests, on both Python 2 and Python 3.
 	detox
 ci:
-	pipenv run py.test -n 8 --boxed --junitxml=report.xml
+	pytest tests --junitxml=report.xml
 
 test-readme:
-	@pipenv run python setup.py check --restructuredtext --strict && ([ $$? -eq 0 ] && echo "README.rst and HISTORY.rst ok") || echo "Invalid markup in README.rst or HISTORY.rst!"
+	python setup.py check --restructuredtext --strict && ([ $$? -eq 0 ] && echo "README.rst and HISTORY.rst ok") || echo "Invalid markup in README.rst or HISTORY.rst!"
 
 flake8:
-	pipenv run flake8 --ignore=E501,F401,E128,E402,E731,F821 requests
+	flake8 --ignore=E501,F401,E128,E402,E731,F821 requests
 
 coverage:
-	pipenv run py.test --cov-config .coveragerc --verbose --cov-report term --cov-report xml --cov=requests tests
+	pytest --cov-config .coveragerc --verbose --cov-report term --cov-report xml --cov=requests tests
 
 publish:
 	pip install 'twine>=1.5.0'
@@ -25,4 +25,4 @@ publish:
 
 docs:
 	cd docs && make html
-	@echo "\033[95m\n\nBuild successful! View the docs homepage at docs/_build/html/index.html.\n\033[0m"
+	@echo "\033[95m\n\nBuild successful! View the docs homepage at docs/_build/html/index.html.\n\033[0m"