Add tox configuration

Tox manages test environments for all supported Python versions, as
well as linting and formatting tools. On GitHub, the test and lint
steps are kept as close as possible to the Makefile equivalents.

Makefile

@@ -1,27 +1,27 @@
-checkfiles = fastapi_cache/ examples/ tests/
-py_warn = PYTHONDEVMODE=1
-
 up:
 	@poetry update
 
 deps:
-	@poetry install --no-root --with=linting -E all
+	@poetry install --no-root --with=linting --all-extras
 
-style: deps
-	@isort -src $(checkfiles)
-	@black $(checkfiles)
+format: deps
+	@poetry run tox run -e format
 
-check: deps
-	@black $(checkfiles) || (echo "Please run 'make style' to auto-fix style issues" && false)
-	@flake8 $(checkfiles)
-	@mypy ${checkfiles}
-	@pyright ${checkfiles}
+lint: deps
+	@poetry run tox run -e lint
 
 test: deps
-	$(py_warn) pytest
+	@poetry run tox
+
+test-parallel: deps
+	@poetry run tox run-parallel
 
 build: clean deps
 	@poetry build
 
 clean:
 	@rm -rf ./dist
+
+# aliases
+check: lint
+style: format