ci: test Python 3.11 through 3.15 (#145)

## Summary

Tests the package on every Python it supports, and declares that set.

- A `test` job runs the suite on 3.11, 3.12, 3.13, 3.14 and 3.15 (3.15
is a release candidate until its October release). The existing job
keeps lint, format, type, dead-code and coverage checks on 3.12.
- The classifiers name 3.11 through 3.15.
- Ruff targets py311, matching `requires-python = ">=3.11"`. 3.10, which
reaches end of life in October, was already outside the supported range.
- The new target's UP017 rule moves two `timezone.utc` uses to
`datetime.UTC`, the same object.

## Type of change

- [ ] Bug fix (no breaking change)
- [ ] New feature (no breaking change)
- [ ] Breaking change (existing callers must update)
- [x] Docs, tests, or internal maintenance only

## Public API

None.

## Test plan

The suite was run locally on each interpreter with a separate
environment per version: 1886 passed and 4 skipped on 3.11, 3.12, 3.13
and 3.14. On macOS, 3.15.0rc2 cannot import pydantic-core's published
3.15 wheel (the dynamic loader rejects the binary), which is outside
this package; the Linux job in this PR's CI is the evidence for 3.15.
ruff, format, ty (package and examples), vulture and the full suite on
3.12 pass locally.

## Checklist

- [x] Tests cover the new behavior, and the suite passes locally
- [x] Lint, format, and type checks pass
- [x] Docs and README examples updated if the public surface changed (no
public surface changed)
- [x] No secrets, credentials, or personal data in the diff or the tests

Author: vvillait88

.github/workflows/ci.yml

@@ -57,3 +57,27 @@ jobs:
 
       - name: Tests
         run: uv run pytest tests/ -v --cov=agentscore_commerce --cov-report=term-missing
+
+  test:
+    runs-on: blacksmith-2vcpu-ubuntu-2404-arm
+    timeout-minutes: 10
+    strategy:
+      fail-fast: false
+      matrix:
+        python: ["3.11", "3.12", "3.13", "3.14", "3.15"]
+    steps:
+      - uses: useblacksmith/checkout@v1
+
+      - name: Install uv
+        uses: astral-sh/setup-uv@v10.2.0
+        with:
+          version: "0.12.20"
+
+      - name: Set up Python
+        run: uv python install ${{ matrix.python }}
+
+      - name: Install dependencies
+        run: uv sync --frozen --all-extras --python ${{ matrix.python }}
+
+      - name: Tests
+        run: uv run --python ${{ matrix.python }} pytest tests/ -q

agentscore_commerce/checkout_compute_first.py

@@ -33,7 +33,7 @@
 import logging
 import uuid
 from dataclasses import dataclass, field
-from datetime import UTC, datetime, timezone
+from datetime import UTC, datetime
 from decimal import Decimal
 from typing import TYPE_CHECKING, Any
 
@@ -207,7 +207,7 @@ def _decimals_for_unit(unit_price_cents: float) -> int:
 
 
 def _iso_now() -> str:
-    return datetime.now(timezone.utc).isoformat().replace("+00:00", "Z")
+    return datetime.now(UTC).isoformat().replace("+00:00", "Z")
 
 
 def _default_success_body(app_url: str) -> Callable[[SuccessBodyArgs], dict[str, Any]]:

examples/multi_rail_merchant.py

@@ -40,7 +40,7 @@
 
 import os
 from dataclasses import asdict
-from datetime import datetime, timezone
+from datetime import UTC, datetime
 from typing import Any
 
 from fastapi import FastAPI, Request
@@ -154,7 +154,7 @@ async def _on_settled(ctx: Any, outcome: SettleOutcome) -> dict[str, Any]:
     success = build_success_next_steps(order_status_url=f"{APP_URL}/orders/{ctx.reference_id}")
     receipt = Receipt(
         id=ctx.reference_id,
-        created_at=datetime.now(timezone.utc).isoformat(),
+        created_at=datetime.now(UTC).isoformat(),
         pricing=ctx.pricing.block,
         product=ProductInfo(name="Regulated Goods Cart"),
         payment_status="completed",

pyproject.toml

@@ -19,6 +19,11 @@ classifiers = [
     "Intended Audience :: Developers",
     "License :: OSI Approved :: MIT License",
     "Programming Language :: Python :: 3",
+    "Programming Language :: Python :: 3.11",
+    "Programming Language :: Python :: 3.12",
+    "Programming Language :: Python :: 3.13",
+    "Programming Language :: Python :: 3.14",
+    "Programming Language :: Python :: 3.15",
     "Framework :: FastAPI",
     "Framework :: Flask",
     "Framework :: Django",

ruff.toml

@@ -1,4 +1,4 @@
-target-version = "py310"
+target-version = "py311"
 line-length = 120
 
 [lint]