[MNT] python 3.14 compatibility, python 3.9 end-of-life (#646)

* updates `pyprojecet.toml` to admit python 3.13 and 3.14
* extends CI to test python 3.14 and 3.13
* python 3.9 end-of-life

Author: fkiraly

.github/workflows/main.yml

@@ -18,12 +18,12 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        python-version: ["3.9", "3.10", "3.11", "3.12"]
+        python-version: ["3.10", "3.11", "3.12", "3.13", "3.14"]
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version: ${{ matrix.python-version }}
           cache: "pip"

pyproject.toml

@@ -16,11 +16,11 @@ classifiers=[
         "License :: OSI Approved :: MIT License",
         "Natural Language :: English",
         "Operating System :: OS Independent",
+        "Programming Language :: Python :: 3.14",
+        "Programming Language :: Python :: 3.13",
         "Programming Language :: Python :: 3.12",
         "Programming Language :: Python :: 3.11",
         "Programming Language :: Python :: 3.10",
-        "Programming Language :: Python :: 3.9",
-        "Programming Language :: Python :: 3.8",
         "Programming Language :: Python :: 3 :: Only",
         "Topic :: Office/Business :: Financial",
         "Topic :: Office/Business :: Financial :: Investment",
@@ -59,7 +59,6 @@ optionals = ["scikit-learn", "matplotlib", "cvxopt"]
 requires = ["poetry-core>=1.0.0"]
 build-backend = "poetry.core.masonry.api"
 
-
 [tool.black]
 line-length = 88