Replace Makefile with tox setup in pyproject.toml

We can now remove the Makefile:
- tox does our testing
- GitHub Actions creates releases
- there's no need for a virtualenv anymore

Note that we remove the `safety` step, that's still run in CI
(tests.yaml).

Author: khink

DEVELOPMENT.md

@@ -0,0 +1,24 @@
+# Development
+
+## Running tests locally
+
+To run tests locally, install [tox](https://tox.wiki/) using [uv](https://docs.astral.sh/uv/)
+with [tox-uv](https://github.com/tox-dev/tox-uv):
+
+```bash
+uv tool install tox --with tox-uv
+```
+
+Install Python versions:
+
+```bash
+uv python install 3.8 3.9 3.10 3.11 3.12
+```
+
+To run tests for all Python versions:
+
+```shell
+tox
+```
+
+TODO: Deduplicate Python version list in [tests.yaml](.github/workflows/tests.yaml)

Makefile

@@ -288,7 +288,13 @@ If you wish to learn more about our API, please visit the [Mollie Developer Port
 
 ## Want to help us make our API client even better?
 
-Want to help us make our API client even better? We take [pull requests](https://github.com/mollie/mollie-api-python/pulls?utf8=%E2%9C%93&q=is%3Apr), sure. But how would you like to contribute to a technology oriented organization? Mollie is hiring developers and system engineers. [Check out our vacancies](https://jobs.mollie.com/) or [get in touch](mailto:personeel@mollie.com).
+Want to help us make our API client even better?
+We take [pull requests](https://github.com/mollie/mollie-api-python/pulls?utf8=%E2%9C%93&q=is%3Apr), sure.
+Check out [DEVELOPMENT.md](./DEVELOPMENT.md).
+
+But how would you like to contribute to a technology oriented organization?
+Mollie is hiring developers and system engineers.
+[Check out our vacancies](https://jobs.mollie.com/) or [get in touch](mailto:personeel@mollie.com).
 
 ## License
 [BSD (Berkeley Software Distribution) License](https://opensource.org/licenses/bsd-license.php).

README.md

@@ -22,3 +22,35 @@ exclude_lines = [
     "pragma: no cover",
     "if TYPE_CHECKING:",
 ]
+
+[tool.tox]
+requires = ["tox>=4.19"]
+env_list = ["flake8", "3.12", "3.11", "3.10", "3.9", "3.8", "type"]
+
+[tool.tox.env_run_base]
+description = "Run tests under {base_python}"
+deps = [
+    "pytest",
+    "pytest-cov",
+    "pytest-mock",
+    "mock",
+    "responses",
+]
+commands = [["pytest"]]
+
+[tool.tox.env.type]
+description = "Run type check"
+deps = [
+    "mypy",
+    "types-requests",
+]
+commands = [["mypy", "--config", "mypy.ini", "mollie"]]
+
+[tool.tox.env.flake8]
+description = "Run codestyle check"
+deps = [
+    "flake8",
+    "flake8-isort",
+    "flake8-black",
+]
+commands = [["flake8", "mollie"]]