Drop dev deps redundant with policyengine-core (#920) (#1695)

* Drop dev deps redundant with policyengine-core (#920)

policyengine-core already pulls in pytest and wheel as runtime deps and
ruff, coverage, pytest-cov and towncrier through its dev extras, so listing
them again here only adds maintenance overhead. Mirrors the pattern in the
US package (policyengine-us#4859).

* Restore coverage/pytest-cov/ruff/towncrier as direct dev deps (#920)

The previous commit removed these on the assumption that policyengine-core
would bring them in. That was wrong: they're in core's *dev* extras, and
pip does NOT install extras-of-dependencies transitively. CI broke with
"pytest: error: unrecognized arguments: --cov=..." because pytest-cov
wasn't installed.

What core actually brings in transitively (runtime deps):
- pytest<9,>=8
- wheel<1

So pytest and wheel can stay removed; the other four need to come back.
Updated the comment in pyproject.toml to be explicit about the
extras-not-installed-transitively rule, and corrected the changelog.

Author: vahid-ahmadi

changelog.d/920.md

@@ -0,0 +1 @@
+- Drop dev dependencies that are already brought in transitively by `policyengine-core` as runtime deps (`pytest`, `wheel`), shrinking the install footprint. `coverage`, `pytest-cov`, `ruff` and `towncrier` are kept because they live in `policyengine-core`'s `dev` extras and pip does not install extras of dependencies transitively.

pyproject.toml

@@ -67,17 +67,20 @@ environments = [
 
 [project.optional-dependencies]
 dev = [
-    "ruff>=0.9.0",
+    # pytest and wheel are brought in transitively by policyengine-core's
+    # runtime dependencies, so they're not repeated here. coverage,
+    # pytest-cov, ruff and towncrier live in core's dev extras, which pip
+    # does NOT install transitively when installing policyengine-uk[dev],
+    # so they must be listed explicitly here.
     "coverage",
+    "pytest-cov",
+    "ruff>=0.9.0",
+    "towncrier>=24.8.0",
     "furo<2023",
     "tqdm",
-    "pytest",
-    "pytest-cov",
     "setuptools",
     "sphinx-argparse>=0.3.2,<1",
     "sphinx-math-dollar>=1.2.1,<2",
-    "wheel",
-    "towncrier>=24.8.0",
     "snowballstemmer>=2,<3",
     "jupyter-book>=2.0.0a0",
     "rich",