🔥 build: drop Python 3.9, add Python 3.14 support

Python 3.9 is end-of-life. Bump the minimum supported version to 3.10
and extend support up to Python 3.14 across packaging metadata,
type/lint tooling, and CI.

- requires-python: >=3.9 -> >=3.10
- drop the 3.9 trove classifier, add the 3.14 classifier
- mypy python_version, ruff target-version, pylint py-version -> 3.10
- CI test matrix: ["3.9", "3.13"] -> ["3.10", "3.14"]

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: nstarman

.github/workflows/ci.yml

@@ -40,7 +40,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.9", "3.13"]
+        python-version: ["3.10", "3.14"]
         runs-on: [ubuntu-latest, macos-latest, windows-latest]
 
     steps:

.python-version

@@ -1 +1 @@
-3.9
+3.10

pyproject.toml

@@ -14,7 +14,7 @@ classifiers = [
   "Programming Language :: Python :: 3.11",
   "Programming Language :: Python :: 3.12",
   "Programming Language :: Python :: 3.13",
-  "Programming Language :: Python :: 3.9",
+  "Programming Language :: Python :: 3.14",
   "Programming Language :: Python",
   "Topic :: Scientific/Engineering",
   "Typing :: Typed",
@@ -27,7 +27,7 @@ dynamic = ["version"]
 license.file = "LICENSE"
 name = "optional_dependencies"
 readme = "README.md"
-requires-python = ">=3.9"
+requires-python = ">=3.10"
 
 [project.urls]
   "Bug Tracker" = "https://github.com/GalacticDynamics/optional_dependencies/issues"
@@ -100,7 +100,7 @@ skip = ["uv.lock"]
     '^conftest\.py$',                   # nox test configuration
   ]
   files = ["src"]
-  python_version = "3.9"
+  python_version = "3.10"
   strict = true
   warn_unreachable = true
   warn_unused_configs = true
@@ -113,7 +113,7 @@ skip = ["uv.lock"]
 
 [tool.ruff]
   src            = ["src"]
-  target-version = "py39"
+  target-version = "py310"
 
   [tool.ruff.lint]
     extend-select = ["ALL"]
@@ -151,6 +151,6 @@ skip = ["uv.lock"]
     "missing-module-docstring",
     "wrong-import-position",
   ]
-  py-version = "3.9"
+  py-version = "3.10"
   reports.output-format = "colorized"
   similarities.ignore-imports = "yes"